FEAR AND LOATHING AT HARVARD UNIVERSITY

Dr. Walter Bishop was halfway through his autopsy of a man named Edward Ziegler when the drugs began to take hold.

Ziegler was sixtyish, balding, unremarkable in death as he had been in life, but when he abruptly morphed into an old-school vampire complete with fangs, glowing red eyes, and big, leathery bat wings, Walter began to wonder whether his subconscious was trying to tell him something.

His subconscious had been active of late, more so than usual, and it wasn't just that Fringe Division (what he thought of as 'his' team) was now forced to work with the Other Side, in a tacit, grudging understanding that if they didn't start to cooperate both universes would continue to degrade at an exponential rate. He knew full well his memory wasn't what it had been once, but it seemed to him that in the last several weeks it had begun to betray him more and more. He'd been—well, he didn't quite recall where he'd been: maybe here, in his Harvard lab; maybe in the offices of Massive Dynamic, talking to Nina, and all of a sudden he'd been there, in what they were calling the Bridge Room, a kind of gateway through which citizens of both universes could pass at will. Top secret, of course; you couldn't have just anybody doing it, crossing over like that; the consequences could be unimaginable.

And for Walter Bishop, 'unimaginable' truly was beyond comprehension.

How the Bridge Room had got there none of them seemed to know. It might, Walter thought, be more accurately described as the Elephant in the Room, except it was the Room. Everyone had his or her own theory of where it had come from, of course; talked at length about temporal anomalies and paradoxes and alternate timelines and quantum this and subatomic that, and the upshot was that none of them, when you came down to it, had the faintest clue. So they dealt with it, and got on with their jobs, closing vortexes and investigating anomalous events after the fact in the unspoken knowledge that they were closing the barn after the horse had run away, so to speak, but they kept soldiering on because that was what they did, and because, well, you had to do something.

And Walter did his part, cutting up the strangely deformed bodies they brought him, analyzing blood and tissue and any number of mysterious chemical compounds, and devising theories that sounded, even to his own ears, increasingly desperate. It was what he'd done for the past four years, ever since Agent Olivia Dunham had got him out of St. Claire's and had herself declared his legal guardian in order that he might assist her and the newly formed Fringe Division with their cases.

He recalled little of his time at the mental institution, for which he was grateful; it had long ago faded into a vague, abhorrent memory of cold metal and bleak, unfurnished corridors; the stench of stale piss and vomit and terrible food and industrial-strength cleaner; white-jacketed figures smiling Stepford smiles and asking him inane questions about his family and childhood and feelings and giving him drugs they said would make him better but they only made him apathetic, passive, banal, ordinary. Walter felt his face flush with anger at the returning flash of memory. How dared they, how dared they inflict their primitive witch-doctory on one of the greatest scientific minds of any century?

Then the room rippled, and Edward Ziegler opened blood-red eyes and smiled at Walter with his needle-sharp, white teeth.

"Hello, Walter," said the dead man.

Walter displayed little outward reaction—as an acid trip this was small potatoes and he didn't want to alarm the others, after all—but all the same he felt his stomach clench in sudden anxiety. His damned memory, or rather, the lack thereof, was at fault, he was sure of it. For weeks now, ever since that Bridge Room had appeared, he'd been plagued by the conviction that something was wrong. Something was lost, missing. Something he desperately needed to remember, but when he tried it slipped away like sand between his fingers, dancing just out of reach on the very edge of consciousness. At first he'd dismissed these feelings as a side effect of the recreational hallucinogens with which he dosed himself on a regular basis, all in the name of science, of course, but lately he wasn't so sure.

Scraps of memory, bright-colored, swirled through his mind, flickering like the lab itself was now doing, a kaleidoscope of joy and pain. A boy, running on the beach. Bach and Miles Davis on the piano. A mysterious bald man, nattily dressed. He, Walter, dancing naked through the kitchen to Caruso's Pagliacci, making blueberry pancakes for Olivia and…someone.

"That's it, Walter!" Ziegler pushed himself up to a sitting position on his slab, black bat wings unfolding to fill half the room, eyes alight. "Think! You have a brain, man, or at least, what's left of one. Six impossible things before breakfast, as the White Queen said. Find the key! Remember!" Walter reached into his pocket, feeling for a coin that had appeared there, quite unexpectedly, some days ago. At the very edge of his vision a face, familiar yet unfamiliar, began to take shape…

"Walter, are you okay?" The voice, anxious and full of concern, intruded harshly on his consciousness, disconcerting him. It fragmented the solidifying apparition into a multitude of crystalline shards that flew off in every direction to shatter against the walls, and shocked him, for an instant, into stone-cold sobriety.

"Camasotz!" shouted Walter. The intrusive voice snapped into alignment with a face dominated by worried brown eyes and a mop of black curls, and the whole team stopped whatever they'd been doing to stare at him. Olivia, the other Olivia, Agent Farnsworth; the one who'd spoken, and the new one, Agent Lee. All frozen, caught in the middle of their conversation, mouths and eyes wide with varying degrees of startled bewilderment.

"Dammit, woman, must you interrupt my meditations?"

"Walter, you were falling asleep. On him." Agent Farnsworth pointed to the body of Edward Zeigler, who now lay in peaceful, middle-aged, middle-class, and altogether dead repose, his former sanguinary characteristics gone as if they'd never existed. Pity. He'd been a lot more interesting as a vampire.

"Walter, do you know what killed him?" That was Olivia, his Olivia, sternly official in her plain black suit, hair pulled back into a utilitarian ponytail. She looked restless, as if she needed to be elsewhere.

"No." It was gone. Whatever grand revelation he'd been on the brink of, it was gone; vanished, lost forever. The sorrow and loss overwhelmed him; he wanted to weep, to shout at them, to ask why, but what was the point? What was the point of anything?

Silence stretched into minutes. When it became clear that the monosyllable wasn't going to satisfy any of them, he made an effort to pull himself together and went on, "It appears to be some sort of animal attack, but I won't know what kind until I've done some further analysis. Death must have occurred quite recently; as you can see the blood from the wounds has yet to coagulate."

"He's been dead two days."

"Oh. Well, why didn't anyone tell me?" Indignation made Walter's voice rise.

"We did, Walter. Two days ago."

"Oh. Oh, I see. Well, perhaps our Mr. Zygote-"

"Zeigler," said four voices, all at once.

"Perhaps our Mr. Zeigler suffered from hemophilia, or some similar affliction."

"I'll have his medical records sent over," said Agent Farnsworth.

"Thank you, Aspartame, dear. Also, I'll need to run more tests. I'm going to need a lab, for a start-"

"You already have a lab," said Olivia. Her voice sounded amused yet uncertain, as if she wasn't sure whether the old scientist was screwing with them or not. "You're right here, in your lab. Walter, what does Camasotz mean?"

"What?"

"Camasotz. You shouted it out just after Astrid woke you up."

"I did?"

"Yes, Walter. What does it mean?"

"Er…" He frowned, hesitating.

"A Wrinkle in Time." Agent Lee broke the silence. "It's a book, a science fiction book, by Madeline L'Engle." He shoved heavy horn-rimmed spectacles further up his nose, looking a bit alarmed at being the sudden center of attention. "Camasotz is a 'dark planet', one that's been completely taken over by an oversized, evil brain called IT. Meg and Charles Wallace go there to rescue their father, who's being held prisoner by IT. Great book. It's one of my favorites."

Agent Lee, who'd joined the team just a few months ago after assisting on an odd case involving a woman who couldn't die, had since proved to be a veritable font of that kind of information. Like Astrid remarked soon after meeting him, "He's a geek, but he's an interesting geek."

"Oh yeah, I remember that book." The other Olivia Dunham, the one Walter had nicknamed 'Fauxlivia', spoke up. "We were supposed to read it in high school, for freshman English. Our teacher was kind of whacked—she was always going on about how it was actually a template for real FTL space travel, and Mrs. L'Engle had to hide it in the form of a children's book because the government was trying to cover up that they had the tech, and they'd kill her if they found out. Or something. Like I said, whacked." She traced a circle around one ear with a forefinger, smiling at the memory.

"Or maybe," suggested Agent Lee, "she was just trying to get you to, you know, actually read a book."

"Hey, I read." Dunham's eyes narrowed at the implied insult to her intellect. "In fact, I just downloaded Steig Larsson's new book, The Girl Who Ran With Scissors. In the original Swedish." Put that in your pipe and smoke it, her tone said. Lee's only reply was a sardonic half-smile.

Olivia, listening to them with half an ear, found herself wondering how the conversation had managed to get so far off track yet again. What did A Wrinkle in Time have to do with Edward Zeigler's death, anyway? Apart from the odd, anomalous blood, she wasn't even sure it was a Fringe event. For all she knew, Zeigler was a huge waste of time. Except that his widow, Maureen, was an old school friend of Agent Broyles, active in Boston politics, and the Higher Ups wanted the case solved as quickly as possible. Sometimes Olivia wished they had somebody around who could speak 'Walter', somebody smart enough to translate all his obscure scientific jargon and even more importantly, to act as a mediator; to calm him down and get him to focus when he went off on one of his crazy, drug-fueled tangents. Hell, I could use somebody to calm me down. Sure, she and Astrid did their best, but they were field agents; they weren't trained for that kind of work.

Dunham and Lee were still bickering. Not the good-natured, sexually charged banter Dunham engaged in with her own universe's Lincoln Lee, their repartee held ego-fueled aggression tinged with real malice. How the hell are we supposed to save two whole universes, Olivia thought for the dozenth time, if the few of us can't even get along? She regarded her doppelganger surreptitiously across the room. At their first meeting Dunham had been a bottle redhead who favored primary colors and paramilitary garb, but she was now a blonde dressed in a dark suit and crisp cotton blouse identical to her twin's. Objectively, Olivia knew it was a good idea; both agents could now navigate each other's worlds with ease and fill in for each other on cases as needed, but at the same time it acted as a painful reminder.

A year ago, Olivia, Walter, and a small team had made their way to the other universe on an exploratory mission which ended in near disaster. Olivia had ended up trapped on the other side, a prisoner of that world's Walter, the Secretary of Defense, and Dunham had returned to this universe in her stead. She'd gone undetected for nearly two months, during which time she'd infiltrated Fringe division and taken over every aspect of Olivia's life—working her cases, combing through her classified files, interacting with her family and friends and co-workers and doing her best to undermine the work of Fringe Division. She'd lived in Olivia's apartment, worn her clothes, slept in her bed, even picked out a birthday gift for her niece. That Ella loved the book and Barbie doll and wouldn't let Olivia exchange them rankled far more than having her mail opened and her checkbook balanced by someone who took at best a cavalier approach to basic arithmetic.

Olivia had barely escaped with her life. It had taken her some time to recover from this violation, this identity theft on a grand scale; even longer to recover from the realization that she had been so easily replaced. How could they not have known? And to top it off, her double hadn't yet offered an apology or even seemed aware that she'd done anything wrong.

On the other hand, Dunham knew a guy who knew a guy who'd jerry-rigged Olivia's DVD player so she could now watch all eight seasons of Firefly, which put her in a more forgiving state of mind. To a point.

"Stomach with contents, two pounds seven ounces." Walter's voice interrupted her thoughts. He heaved a dripping organ off the hanging scale and into a metal pan. "Make a note of it, please, Astarte."

Olivia hid a smile. Apart from a slight, exasperated eye roll, Astrid didn't even react any more to Walter's continual mangling of her first name. Both women suspected that he knew Agent Farnsworth's name perfectly well; this was his idea of humor, or perhaps an old man's quiet rebellion against the reality that he was basically dependent on the agents for his livelihood and freedom.

"It appears Mr. Zeigler's last meal was Thai beef with basil," Walter continued. "Jasmine rice. Oh, and a mango lassi." His face brightened. "Dear, perhaps we could-"

"Walter, please tell me that dead body isn't making you hungry." Astrid's expression shifted from resignation to nausea. "It is, isn't it?" She swallowed once, convulsively, then breathed out a long sigh. "All right, look, we'll pick up Thai food tonight, on the way home from work. Okay?"

"Splendid. And now-"

"Gotta go." Agent Dunham broke in, one hand to the otherworldly earpiece she used to communicate with the rest of her team. She appeared to listen for a moment. "Okay, be right there. Love to stay and chat with you all," she told the room at large, "but they've found another body. Allston, this time." She rattled off the address. "You guys coming?" Without a word, Agent Lee picked up his coat and walked past her to the exit.

"We'll catch you up," Olivia said. "Astrid and I just need to have a word first." Dunham nodded and turned to go.

"Be careful out there," Walter told her retreating back. "This is bat country."

Dunham froze in her tracks, her face registering incredulity and, as Olivia noted with satisfaction, terror. About time something wiped that smug smirk off her double's face. "You're freaking kidding me, right? Bats?"

"Don't worry, it's just a quote," Astrid hastened to reassure her. "Fear and Loathing in Las Vegas, isn't that right, Walter?" He nodded. Dunham looked blank, but some of her panic faded.

"You know, Hunter S. Thompson? Er, Johnny Depp?" Dunham shrugged and shook her head, looking blanker than before, and Astrid gave up. "Never mind. We'll be with you shortly. Just have a few things to clear up here first.

"You know," she added when the door had shut behind Lee and Dunham, "the other universe really got shortchanged in the pop culture department. No Johnny Depp, no U2, no Humphrey Bogart, and Pete Best never left the Beatles. No wonder they get so…testy."

"At least their John Lennon is still alive." Olivia watched the retreating forms of the two agents as they made their way down the corridor. They appeared to be arguing again. Testy, she thought, wasn't the word for it.

"Yes, but at what cost?" Walter looked up from his handiwork on the slab. "Do you realize Lennon never even wrote Imagine in their world? Now, he's recording duets with Tony Bennett and making commercials for Priceline. Jimi Hendrix is probably hosting a reality show." He huffed out a sound halfway between disgust and laughter. After a moment, Astrid gave an answering grin.

"Come on, Walter, button it up and get your kit," she told him. "We've got another body for you. What did you want to talk to me about?" she asked, transferring her attention to Olivia.

The other agent jerked her head toward the small office just off the lab. "In there."

When they were both seated in the office with the door closed behind them, Astrid said, "What's going on?"

Olivia looked around as if afraid of being overheard before leaning toward the other woman and answering in a low voice, "I saw it again last night."

"It?" Astrid's eyes widened. She spoke in the same low voice. "You mean him."

"I mean it. 'Him' would imply that I'm ascribing human characteristics to it, which in turn implies that I'm starting to believe it's real." She shook her head as if to clear it, her voice rising. "Astrid, what if I start seeing this—this thing out in the field? If Broyles finds out I'm suffering from hallucinations, he'll stick me behind a desk and make me go for all kinds of medical and psychological testing. I can't go crazy now. If the Walters are right, we're all living on borrowed time here. I need to be out in the field and at the top of my game if we're going to find a way to save both universes."

"Okay, calm down." Astrid frowned, thinking. "First of all, are you sure it's a hallucination? How do you know it isn't a shapeshifter, or a hologram, or…I don't know, someone from a third universe? One we don't know about yet?"

"It isn't a shapeshifter. It doesn't act like one. And holograms aren't this sophisticated, except in the movies."

"What was he—I mean, it doing?"

"Nothing. Just standing out on the sidewalk looking at my apartment. It was raining last night, but he didn't get wet. His hair and the pea jacket he was wearing were both perfectly dry. He was kind of transparent, too—I could see the trees and the buildings across the street through him. And the light was all wrong. See, he was standing to the right of the streetlight," Olivia explained, using the desk lamp and a Star Wars action figure to demonstrate. "The light should have been shining down on him from the left, but it wasn't. It was all around him, and it was a different color. Blue, when it should have been golden." In her distress, Olivia didn't seem to notice that she also was now using the personal pronoun. "And this is the weird part-"

"There's a weird part?" Astrid's voice was ironic.

"It was a shade of blue that doesn't exist in this universe. It's like he was here but in some other reality as well."

"Like I said, third universe." Astrid nodded knowingly. "Or, wait—here's an idea. Remember when we first started out in Fringe Division, you shared consciousness with Agent Scott?"

Agent Scott. John. That felt like a lifetime ago, the pain a distant memory. "Yeah, so?"

"Well, you started picking up his memories and thinking they were your own, right? So, maybe it's happening again. Maybe this guy is somebody Agent Scott knew. Somebody he was investigating. He could be sending you a message." Astrid stood up. "There's one way to find out for sure. We can have Walter prep the tank and-"

"No." The word came out louder than Olivia had intended, her voice cracking with tension. "I don't want Walter to know about this. He means well, but if he lets something slip to Broyles or the others, I'm finished. And I'm not going back in that tank again. You couldn't pay me enough. Besides, it's been almost four years. Why would I suddenly start picking up John's memories again now? No, this is…" She spread her hands, searching for the right word. "This is…personal. It has nothing to do with John. Don't ask me how I know, but I do."

She'd thought the pain of losing John was gone for good. She shouldn't be feeling this overpowering sense of loss that Astrid's words brought back to her, shouldn't feel this sudden rush of isolation, of wrongness with the universe. There is a great disturbance in the Force, she thought, and flicked the action figure with a finger, sending it skittering across the desk. Something was gone, something was missing, leaving her bereft, almost ill with the feelings that threatened to overwhelm her.

After John's death she'd compartmentalized her pain, pushing it to a tiny corner of her mind, boxing it away so it couldn't break out and distract her from her work. There hadn't been anyone else. That one-night stand with Lucas in Germany didn't count. So why was she suddenly waking up every morning on one side of the bed, reaching for someone who wasn't there? Why did she keep getting two whiskey glasses out of the cupboard when she was the only one in her apartment? It made no sense. Unless…maybe it is about John, she thought. I guess I never really dealt with it properly.

Astrid was silent for a long moment, watching her friend's face, but at last she nodded. "Okay. So, what do you want to do? We shouldn't just ignore this."

Olivia rubbed her hands over her face, trying to push away the bad feeling, telling herself to focus, focus. Don't lose it now, Dunham. Two universes need you. "Maybe it's just stress. Overwork." Yeah, that's it. " I haven't been sleeping well lately; I keep having headaches, these dreams…you know, that could be it. A waking dream, a manifestation of my subconscious mind at work. If I figure out what my subconscious is trying to tell me, the visions will go away, and I'll be fine." Olivia tried for a confident smile, looking, Astrid thought, even more tense than before. "Thank you, Astrid."

For what? Astrid thought. She looked doubtfully at Olivia, not at all convinced by her facile explanation. But hey, whatever helps you sleep at night, girlfriend. She forced a smile of her own. "Now you sound like Walter."

"God forbid." Olivia stood up. "Come on, let's collect him and go join the others. They're waiting for us."

"Right behind you," said Astrid, keeping her doubts to herself. "And if you change your mind…" She looked meaningfully toward the door and the lab beyond. "I know a guy who has plenty of experience with the crazy."

Just after midnight, Olivia Dunham unlocked her apartment and switched on the light. Even though it was a quiet neighborhood, relatively untroubled by crime, she did her customary sweep of the apartment, weapon drawn, every sense on high alert. She checked each room systematically for possible intruders, even peering under her bed and into closets and cupboards and behind doors. Finally, satisfied yet still on edge, she replaced the safety on her Glock and laid it within easy reach on the kitchen counter.

They hadn't made much progress with the new case, except to confirm in Olivia's mind that it was, in fact, a case. The second victim had died of bite wounds similar enough to Edward Ziegler's to suggest an identical cause of death, except this one, a Harvard law student named Janice Taylor, had been almost completely drained of blood. Bat country, thought Olivia, and repressed a shudder. Apart from the curious MO, Taylor had no connection to Ziegler that the team could find. For now, they were working on Agent Lee's theory that both were cult murders by vampire fetishists, part of Boston's Goth underground.

Olivia had her doubts. Regardless of what the tabloids said, cultists weren't all that common, and the few vamps she'd met over the years were quiet, non-violent types for whom blood exchange was a consensual act.

Their one person of interest so far was a washout as well. The description of a well-dressed Hispanic man in his fifties seen talking to both victims matched that of one Dr. Alvaro Acosta of Mérida in the Yucatan Peninsula, in town for some sort of medical conference at the Hyatt Regency. Unfortunately, Acosta had alibied out, his whereabouts at the presumed times of death confirmed by about a hundred witnesses, so they were now back to square one.

And the medical records faxed over to the lab had confirmed that whatever Edward Zeigler had been, he most definitely wasn't a hemophiliac.

Meanwhile, Olivia's double was sulking. Something Dunham had eaten earlier disagreed with her, and her chupacabra theory, drawn from the Central American connection, had been openly sneered at by Agent Lee. "This isn't the damn X-Files," he'd snapped at her. "And we're not cryptozoologists. Get real." She'd declined the offer to join Walter and Astrid for Thai carry-out and headed back to the Bridge Room and her own universe in a snit, remarking that at least one of their number was going to get laid that night.

It gave Olivia a headache just thinking about it. Thank God she was home now, in her own apartment, where it was quiet except for the low-level hum of the air conditioner, and if she couldn't fully escape the pressures of the day, she at least knew how to deaden them. Tossing her jacket and shoulder holster more or less in the direction of the sofa, she untucked her blouse and made a beeline for the kitchen cabinets, where she pulled out a half-bottle of Old Crow and sloshed a generous two inches into a highball glass. Tossing it off a a gulp, she poured another.

"You used to drink the good stuff."

The voice, male and faintly amused, issued from her living room. Olivia spun around and managed not to drop the glass, but she did slam it down hard on the granite countertop, sloshing whiskey onto her hand. It sounded like a gunshot in the quiet apartment. She looked up, and there stood Hallucination Guy watching her, looking cool and relaxed, hands in the pockets of his merchant navy pea jacket. Despite the fact that it was August and they were in the middle of a heat wave the rain couldn't alleviate, he wasn't even sweating. The same weird blue light she'd seen last night glowed all around him, giving him an otherworldly appearance.

In an instant Olivia had her gun in hand, safety off, the barrel pointing straight at the fake guy's heart. "Budget cuts, tough economy, you know how it is." Her voice and hands, she was pleased to note, didn't shake at all. Though why she was even talking to something that clearly didn't exist, much less pointing a gun at it, was the real issue.

The hallucination didn't act remotely alarmed. He grinned at her and strolled a few steps forward, laughing silently in such a familiar, intimate manner that she almost smiled back until he flickered, wavering in and out of existence in a way that made her feel ill. Slowly, she eased the safety back on the Glock and set it down on the countertop, the muzzle pointing away from both of them. The transparency and flickering made Olivia's headache worse. She wiped her damp fingers on her pants and took another drink, closing her eyes against the wrongness of the image in front of her.

"Temporal paradoxes are a bitch, aren't they?" The guy spoke again, auditory hallucinations now, I really am losing it, and she opened her eyes to find him smiling at her. He had even, white teeth, and his eyes were very blue. Ironic, Olivia thought, that the hottest guy to set foot in her apartment in damn near four years was a figment of her imagination. Not to mention depressing, pathetic, and a few other adjectives she didn't want to think too hard about.

"I mean," the guy went on, pointing to something in her bookcase, "that shouldn't be here either, and yet it is."

Curious, Olivia went to look where he was pointing. The book was a slender hardcover, its wrapper stark white with plain black lettering. If You Meet the Buddha On the Road, Kill Him! She blinked, wondering how she'd overlooked it, incongruously mis-shelved as it was in the middle of a row of mystery novels by Richard Castle. She pulled it out and flipped it open, and a sheet of paper fluttered. She caught it before it hit the ground and read the words handwritten in unfamiliar script: Because you asked.

"Someone gave it to me. I think." Olivia frowned, head aching even more with the effort of focusing her thoughts. "Rachel, probably." Her sister was notorious for leaving things like holiday shopping to the last minute and then grabbing any old thing, safe in the certainty that the unenthusiastic recipient would exchange it for something they really wanted.

Of course, that wasn't Rachel's handwriting, but that didn't mean anything. The paper could have got there by accident.

"Course correction," the hallucination said, nodding in a knowing way. "The universe re-aligning itself to fit with a new reality. Which of course, isn't new, because it's already happened several times over, in different iterations. And is still happening. Like I said, a bitch."

There was something achingly familiar about this man, and yet—there wasn't. "Do I know you?"

"You do, but then again, you don't. You will, but you won't. You did, but-"

"-I didn't. Okay, got that. Are you a ghost?" Olivia didn't believe in them, but right now she was prepared to consider just about any impossibility.

He shook his head. "Dead is too simple. Reductive. Absurd." He spread his hands wide, an all-encompassing gesture. "Life and death…these are relative terms. Contextually defined, dependent on cultural specifics."

"So…not dead, then. Un-alive? Never existed? Except you did—do?"

The guy gave her a thumbs-up. "Now we're getting somewhere." I should introduce him to Walter, Olivia thought. They speak the same language. She felt a laugh bubble up at the thought. Walter, meet my own private hallucination. I think the two of you will get along.

"So you're saying…" She pinched the bridge of her nose, trying to force her scattered thoughts into some kind of order. A term she'd heard Walter use surfaced. "You're saying you're…Schrodinger's Cat?"

"Meow," said the guy, and he grinned at her again, so familiar and loving and full of life that against every instinct she smiled back until his expression shifted, and he stared past, no, through her at something only he could see, something out of a nightmare.

"You don't know what it's like here, Olivia," he said, his voice shaking, urgent. "The things that live here…every childhood nightmare, every terrifying legend, is real. Bad waves of paranoia, fear and loathing—intolerable vibrations in this place. Get me out of here, Olivia. Find the key. If anyone can do it, you can."

"I—I don't-" she began. And then her phone bleeped, making her jump.

Pushing aside her annoyance—it's almost one o' clock in the damn morning! What could anyone possibly want now?—she glanced at the text message. It was from Dunham, who enjoyed the (for her) otherworldly tech and used it at every available opportunity.

"HEY, E.T.! DUTY CALLS! MORE BODIES!"

Olivia frowned, torn between duty to her team and desire to learn more about this man, to try and help him if she could. E.T. in this case stood for Evil Twin, her doppelganger's idea of a joke. It had been kind of funny the first half-dozen or so times. Now, not so much. She thought uncharitably of a well-known fantasy author's assertion that multiple exclamation points were a sign of a diseased mind, and then reminded herself that she was the one standing there talking to a guy who didn't exist. Before she had a chance to respond, though, the phone bleeped again, and the text was replaced by a new one. "PICK UP W. AND GET OVER HERE!" An address in Cambridge followed.

"I have to go," said Olivia, looking up. The man was gone.

The alley that backed the Harp and Dragon Pub in Cambridge resembled every other alley in every city in America at one AM. Dark and sinister, illuminated only by ambient light from the street, it held a Dumpster overflowing with trash, more piles of reeking unidentifiable rubbish, and stank of urine, feces and vomit. Loud rock music issued from the pub itself, in front of which a curious crowd had gathered, kept at bay by crisscrossed yellow police tape and a couple of uniformed officers.

Agent Lee met Olivia as she made her way to the opening of the alley, Astrid and Walter hard on her heels. The latter carried the case that held his forensics equipment and wore the expression of a kid on Christmas morning.

"Where are the bodies?" he asked.

"They're in here," Lee said, gesturing. "Same MO as the others. Two this time. Guy walking his dog found them, called it in from his cell phone. He didn't see anything else useful, so I took his statement and let him go home."

"Let me guess," said Olivia, as she switched on her flashlight and got her first glimpse of the newest victims. "Actors." She tried not to think too hard about the man in her apartment and the disturbing feelings his presence had generated in her. Focus on what's in front of you.

"Close. Historical re-enactors, actually. The battle of Bosworth Field, according to the bartender. Today—or rather yesterday—was the anniversary of the battle. August the twenty-second, fourteen-eighty-five." Lee bent over the recumbent figures, which were huddled together near the mouth of the alley. One had long black hair and a red and blue tunic emblazoned with a white boar; the other, a stocky blond, wore a similar garment decorated with a red dragon. Both men wore shirts and gauntlets of faux chain mail. The alcohol fumes coming off them were almost palpable. Walter immediately knelt and began examining their wounds with alacrity, muttering under his breath all the while. He took swabs of the wounds and remaining blood and placed the samples in sterile jars.

"From the costumes, I'm guessing these two played the roles of Richard III and Henry Tudor," Lee went on. "Looks like Richard, whose real name, by the way, is Stanley Whipple, tried to fend off whatever it was that attacked them with this-" and he moved aside the first man's cloak, exposing a very long, sharp, very real broadsword, still clutched in his right hand. "But they were both so drunk they didn't stand a chance."

Walter touched the sword gently with one gloved hand, admiring its design. "Amazing engineering. Beautiful work, too. It's the real thing, not a prop. I played Hamlet back in '71, you know. An all nude production, very avant-garde. Acquired a bit of unexpected subtext when Polonius got an erection at his first sight of Ophelia." He chuckled and turned back to his examination of the bodies.

"They've been dead an hour and a half at most." Dunham joined them from the steps of the pub, where she'd been interviewing witnesses. "After the mock battle ended, they went to the bar for dinner and had several drinks each, played some pool. They left together on foot around eleven-thirty. If anyone saw or heard anything, they're not talking." She took a long look at the victims' livid, bloodless faces, and abruptly doubled over, vomiting against the alley wall. The others watched her in astonishment.

After a moment Dunham straightened up, wiping her mouth with the back of her hand, her face very green in the half-light. Astrid wordlessly handed her a bottle of water, which she accepted with thanks. "Don't worry, I'm not getting squeamish on you," she said. "Damn burger I ate for lunch. What is it with the food in this universe, anyway?"

"Maybe you're pregnant," Lee suggested, and Dunham snapped her head around toward him so fast she practically gave herself whiplash.

"What?"

"Hey, as you're fond of reminding us, you're the only one here who has a personal life," he said, shrugging. "And condoms have been known to break, you know."

"Listen, dork." Dunham advanced on him, hands on hips, mouth set in a straight line. "My universe hasn't used condoms for fifty years. We're well beyond such primitive stop-gaps."

"Guys, crime scene." Astrid intervened before the guns came out and more blood was spilled. "Try to focus, okay? We're on the same side here."

"You sure about that?" Lee eyed Dunham through narrowed eyes. "I've read the files on her. I know all about what she got up to the last time she was here, what she did to Olivia-"

"That was just an assignment. It wasn't personal."

"She's right," Olivia put in. One of them had to be the adult, after all. "Linc, it's very sweet of you to defend me, but we're past that. It's over." Not waiting for any of them to respond, she played her flashlight over the darkness at the other end of the alley and began to walk that way. "Where does this lead?"

She'd gone maybe ten feet when she stumbled over what appeared to be a pile of old rags. As she put one hand against the wall to steady herself, the rags shuddered and rose up with a strangled, horrifying scream, revealing a more or less human figure which leapt to its feet and pelted down the alley into the shadows. Olivia gave chase. It didn't take her long to catch up with the runner, who turned out to be a gaunt, pasty man of indeterminate age. Hair and beard were both long and matted, he wore an assortment of tattered clothing, and was sweating and shaking uncontrollably, his breath coming in hoarse, ragged sobs.

"FBI," Olivia told him, holding the man with one hand and keeping her Glock trained on him with the other. "What are you doing in this alley?" The man didn't seem to hear or notice; he was too far inside some nightmare world of his own.

"Bats!" The word issued from his throat in a croak. He thrashed in Olivia's grip and flailed about him at some invisible adversary. His voice rose. "Big, goddamned bats!" Tightening her grip on his collar, Olivia half pushed, half dragged him back toward the others.

"Did I hear you say bats?" Walter rose to his feet to meet them, eyes alight with curiosity. "Describe them, please, young man."

"Walter, this guy's stoned out of his gourd," Dunham pointed out. She'd gone rigid at the mention of bats, Olivia noted, her eyes wide, hands clenched into tight fists. "He isn't going to know anything."

"Open your mind, girl, the two are not mutually exclusive," Walter admonished her. He turned back to the captive. "Now, sir, who are you?"

The man turned his pale, almost colorless eyes with pinpoint pupils on Walter and giggled. The laugh went on a long time, growing deeper and rising in volume to become a full-throated Evil Overlord cackle before trailing off into a fit of coughing that somewhat ruined the effect. Astrid and Lee exchanged skeptical glances. Walter waited, saying nothing, his eyes fixed on the man.

"I am the wind that stirs the trees at midnight," said the man at last, his voice hoarse from coughing. "I am the clouds over the moon…and my name is Emmanuel Watrous. You may call me Manny."

"Very well, Manny," said Walter. "Tell me about these bats, if you please."

"The knights…the knights came into the alley. They were holding each other up, singing." Manny licked his lips, his eyes darting wildly from one face to the next. "Suddenly there was a terrible roar all around us, and the sky was full of what looked like huge bats, all swooping and screeching and diving around the alley and a voice was screaming: Holy Jesus, what are these goddamn animals?" Manny's own voice rose to a near scream. He swayed and shuddered in Olivia's grasp and looked ready to pass out.

"Camasotz," Walter whispered. He nodded to Manny, one kindred soul to another. "What happened next?"

"The tall knight drew his sword. He tried to fight them, but there were too many. It was all over quickly." Manny's voice sank to a hoarse whisper. "I hid in the shadows, and they didn't find me. Then the man came."

"What man?" Olivia asked, and Manny looked at her as if he'd forgotten she was there.

"A man like a Mayan idol, but he wore a suit."

"He could mean Dr. Acosta," said Agent Lee. "He's short and heavyset."

Manny said, "He had a black box with buttons. He called the bats with it, and they went back."

"Back? What do you mean, back? Where did they go? Into the box?"

Manny shook his head vigorously. "No, no. Nononononono…" His voice trailed off and he lapsed into silence, his eyes unfocused. A thin trickle of saliva ran from one corner of his mouth.

"Manny, pay attention!" Walter's voice rang out in the silence. "This is important. Where did the bats go?" Manny shivered and blinked. His jaw trembled.

"Back into the spaces between the universes, of course," he said in a calm, reasonable voice. "I think I'd like a drink now." His eyes rolled back in his head, and he collapsed in a heap at Walter's feet, out cold.

"Of course, of course. I could go for a strawberry milkshake myself." Unfazed, Walter beamed down at the supine junkie. "Thank you, Mr. Watrous, you've been extremely helpful. I'm beginning to understand everything, now."

"Oh, good, I'm glad one of us is," Dunham muttered. Walter gave her a reproachful look.

"Do try and keep up, dear. The meaning of Camasotz—the original meaning, that is, not the one from Mrs. L'Engle's splendid book, which I suspect was chosen for sound rather than sense," he added with a glance at Agent Lee. "The unique properties of the saliva of Desmodus rotundus, the common vampire bat. And of course, the Mesoamerican connection. I think we need to locate Dr. Acosta as quickly as possible, don't you?" He looked around at the assembled agents. "Do any of you know what the topic is of this conference he's attending?"

"Something to do with cerebrovascular disease," said Olivia. "Stroke research, I think-" and Walter gave a sharp gasp, clapping his hands together and almost dancing in place in excitement.

"Of course! The last piece of the puzzle falls into place. Fish, I must have fish."

"Fish? I don't understand," began Agent Lee, and Astrid gave him a look and said, "Just go with it."

"Brain food, idiot boy," said Walter. "The vitamin D stimulates cognitive function." He knelt and began packing up his case, beckoning one of the uniformed cops forward. "Have these bodies taken to my lab at Harvard at once, please. And get our friend Mr. Watrous here a drink."

The uniform looked puzzled and not a little outraged at being ordered about by a civilian, until Astrid took him aside and said, "It's okay, he has clearance." She smiled up at him, turning on the full force of her charm. "We really need those bodies. And can you get someone to take our witness to a hospital, please? He's unconscious, and really should be checked out by a doctor. I hate the thought of him spending the night in this alley."

Things began to move rather swiftly after that.

About an hour and a half later the team found themselves seated at an all-night diner. They'd managed to locate one that had a fish and chips special, and the two Olivias, Astrid, and Lincoln Lee sat around watching Walter eat, drinking coffee to stay awake and waiting for him to explain what was going on. Typically, now that he had their full attention, the old scientist was at his most enigmatic and evasive. Not to mention larcenous—they'd all seen him quietly remove the broadsword, which he'd clearly taken a fancy to, from Stanley Whipple's grasp and slip it under his raincoat before the body was bagged and loaded into the police van. No-one had said anything. It was a long night and everybody was tired; may as well let him have his fun.

Meanwhile, locating Dr. Acosta was proving easier said than done. The desk clerk at the Hyatt Regency had confirmed that he'd checked out of his room several hours ago, but no-one had seen him leave or had any idea of where he might have gone. The FBI had put out an APB on him and also issued his description to Logan Airport, the train and bus terminals, and the local news stations in case someone spotted him trying to leave town.

Olivia stretched, trying to ease the stiffness of her muscles in the cramped booth of the diner. She stifled a yawn. "Walter, it's getting late, or rather, early. Please don't keep us in suspense any longer."

"Very well." The old scientist looked up from his plate and at the captive audience before him, delighted at the chance to share some new piece of knowledge. "The common vampire bat," he began, "is far from common—in fact, he is one of nature's most extraordinary creatures. He has in his saliva a compound known as DSPA—an anticoagulant that prevents his bite from sealing up and allows him to drink his fill from a victim. During the course of some government-backed research in 1979, I theorized that this compound could be collected—or synthesized—to treat a number of ailments, including blood clots in the brain that cause stroke. It would appear that mainstream medical thought has finally caught up with me, at least in that area." He paused to swirl a French fry in ketchup before popping it in his mouth and chewing.

"The difficulty I ran into, of course," he went on, "is that the vampire bat is quite tiny, little more than a mouse with wings. When it became clear that it would take dozens—perhaps hundreds—of the creatures to collect enough DSPA for practical use, the government bosses suggested I concentrate on some other area of research.

"Now, I think it quite probable that Dr. Acosta looked at the problem from the same angle as I did, and he said to himself-"

"'We're gonna need a bigger bat,'" muttered Agent Lee, and then said, "Ow!" because of something that Astrid did to him under the table at that moment.

"Indeed." Walter beamed his approval. "Which brings us to Camasotz—its original meaning, as I believe I mentioned earlier." He slurped some of his milkshake noisily through a straw, and grimaced. "Passable at best. Fresh, not frozen strawberries, are the key to a good milkshake. Remember that. Now, where was I? Ah, yes, Camasotz. The ancient Maya had a legend of a terrifying demon in the shape of a giant vampire bat, that came out at night to suck the blood of the living. They called this demon the Camasotz, or snatch-bat." His voice fell to a sinister whisper. Dunham made a small, convulsive movement that spilled coffee into her saucer.

"Now, legends have several different origins, of course, many of them spurious. But the jungles of Central America are dense and still unexplored in some areas, and it's possible—indeed, probable—that a new species of vampire bat, as yet undiscovered by the scientific community, lurks there in the shadows, waiting and watching for its prey. Desmodus giganticus, the Camasotz of legend. I believe Dr. Acosta may actually have captured a few specimens for research purposes."

"And he brought them here for the conference, and they escaped," said Astrid. "If you're right, Walter, we need to find Dr. Acosta right away. Those things could be anywhere."

"Or nowhere," said Olivia. They all looked at her. "Remember what Manny said? He said Acosta called them with some kind of device, and they went back into the spaces between the universes."

"You don't seriously believe everything that guy told us, do you?" Dunham said. "I mean, he's crazier than-" She broke off with a glance at Walter, her cheeks turning pink.

"Perhaps not." Walter took another fry. "Perhaps Doctor Acosta, like us, has discovered a way to travel safely between worlds. The bats could be from the other universe."

"Not mine." Dunham shook her head. "All species of bats have been extinct in my universe for years. The vampires were one of the first to go. Thank God." She shuddered. Agent Lee's phone chimed, and he lifted it to his ear, turning away to listen.

"Third universe," said Astrid, meeting Olivia's eyes.

"Dear God, I hope not," said Walter. "One other version of me is one too many."

"They've found him." Lee put his phone down on the table and stood up, reaching for his raincoat. "Dr. Acosta. He's at Logan airport. He just got on a flight leaving for Mexico in fifteen minutes. Come on."

The other agents rose at once to join him, setting down coffee cups and scraping back chairs. "Don't let that plane leave the ground," Lee said into his phone. "We're on our way." He and Astrid headed for the door in a rush, Dunham close behind them.

Walter looked at his plate. "But I haven't finished my-"

"Leave it, Walter." Olivia tossed a few bills onto the table. Then she took Walter's arm and hustled him out the door to join the others.

"Goddamned bats!" said the man from TSA. He pulled out a stained bandanna and wiped his face, which was streaked with rain and sweat. His hands shook. "We had Acosta in custody, I swear. He went quietly. He was clean. No weapons, no drugs, nothing. Everything's kosher, right? Then my buddy Mike gets a call on his phone and turns away for just a second, and Acosta pulls up the sleeve of his coat and there's this thing strapped to his arm, like a little box. Dunno how we missed it. He starts pushing buttons, and suddenly these—these creatures come out of nowhere." He licked his lips.

"Bats! Biggest fuckers you ever seen! Dozens of 'em. Bigger than any bird. Swooping and shrieking and biting people—it was chaos. Everybody's screaming, running for their lives. Then, all of a sudden, they're gone. And Acosta's missing, too." He dropped into a chair like a marionette with its strings cut and wrapped his arms around his trembling body. He looked anxiously up at Olivia. "Am I gonna lose my job over this?"

"Don't worry, Mr.-" Olivia glanced at the man's badge. "Mr. Dysart. I'm sure you did the best you could under the circumstances."

"Ya think? 'Cause I got a family to feed-" He broke off as Agent Lee came up at a dead run, weapon drawn. He pulled up short at the sight of Olivia.

"Acosta's been spotted on the runway," he said between gasps for breath. "More bats. Hurry!"

"Thank you, Mr. Dysart, you've been a help," said Olivia, and allowed Lee to half lead, half drag her out through a side door and onto the tarmac. They burst onto a scene of chaos, with passengers and crew of Acosta's flight all milling around near the plane in anger, fear, and confusion. Shouts, screams, and sobs drowned out the TSA employees, uniformed cops, and airline personnel who were trying to keep the situation under control. Air hostesses handed out bottled water and applied first aid, while the pilot and co-pilot exchanged shifty glances and passed a flask of something back and forth. Astrid and Dunham were interviewing a few of the calmer passengers, and Walter was busy scraping some kind of substance off the tarmac and muttering to himself.

Then Olivia spotted a small, stocky figure of a man moving furtively along the very edge of the runway, partly masked by a dark line of trees. The man's head turned. He caught sight of her and began to pick up speed, his long coat flapping about his ankles as he ran. Olivia matched his pace, drawing her Glock. Agent Lee split off from her and headed in the opposite direction, most likely to double back and cut the man off from the other side. As Olivia ran, she saw the man fiddling with what looked like a small rectangular box strapped to his left arm.

"FBI, Dr. Acosta! Stop!" And as she pounded after him, booted feet echoing on the tarmac, the bats came back.

They swooped out of the night sky, dozens of them, diving and shrieking with a noise like multiple train whistles, flickering with the same otherworldly blue light Olivia had seen around the man in her apartment. As people screamed and ran or clutched their heads and moaned at the cacophony of light and sound, the bats attacked. Biting and scratching, they knocked people to the ground with their huge, leathery wings, even snatching up and carrying off a few smaller individuals. Screams rang out as everyone panicked and ran off in every direction.

Olivia made herself ignore the swooping, screaming animals and concentrate on Acosta, who had slowed to push more buttons on his device. When he paused to triangulate his position, she took the opportunity to close the gap between them. She saw Lee, running toward them both from the opposite direction, shouting something she couldn't hear, waving to get her attention. His mouth moved and he kept pointing at his wrist with the hand that didn't hold a gun, and she shrugged as she ran, trying to figure out what it was he was saying to her.

"Aim for the box, aim for the box." Lee kept yelling at Olivia even though he knew it was futile, knew she couldn't hear him over the shrieks of the bats and their victims. "That's how he's controlling them." He tried to draw a bead on Acosta, but Olivia was in the way, and he couldn't risk hitting her by accident. "Jesus Christ, Olivia, shoot the goddamned box." Olivia shook her head in incomprehension and kept pace after Acosta.

"Dunham, people are dying." Astrid's voice, urgent and on the edge of panic, penetrated the agent's brain, which had shut down as soon as the first dark shapes dove out of the sky. She was dimly aware of Farnsworth removing her gun—her gun! from its holster and pressing it into her hand, something she'd never have tolerated under different circumstances. She felt her fingers curl around the grip but could no more raise the weapon than she could fly. All of a sudden, a bat detached itself from the main concentration of people and flew directly at her. It stopped in midair, hovering a foot or so from her face, so close she could see her own reflection in its beady black eyes, and opened its maw to reveal two-inch-long, razor sharp fangs dripping with human gore. Dunham froze, unable to move, paralyzed with terror at the sight of every childhood nightmare she'd ever had made flesh.

Walter gazed, entranced, at the bats. They were the most magnificent creatures he'd ever seen—graceful, elegant ebony shadows wheeling through the night sky; exquisite, perfect killing machines. Not of this world, or any world in any sense of the word, but somewhere else, somewhere in between. "Beautiful, beautiful," he exclaimed, as one flew close to him, raking his coat sleeve with its claws and shredding the fabric. Then the bat banked and executed a U-turn to come back for the kill, and Walter took a step back, his eyes widening. He reached under his coat and silently slid Stanley Whipple's broadsword from its scabbard. The bats were glorious, he thought, resplendent. Too bad they had to die.

Astrid had her hands full, trying to keep the panicking crowd under control. She tried several times to take a shot at one of the bats, but there were too many people, civilians, in the way, for her to find a clear target. Instead, she concentrated on helping two of the air hostesses herd the passengers back inside the plane where the bats couldn't follow. Children were crying, parents screaming for their children, and the bats were everywhere—dozens of them, hundreds. They materialized out of thin air, flickering with an unearthly blue glow that jogged Astrid's memory, but she didn't have time to think why or how. She had a job to do.

Olivia saw Acosta change direction and start to run directly toward the crowd near the airplane. If he got too close, she'd never get a shot at him without endangering civilian lives. It's now or never, she thought, and raised her Glock. Agent Lee was still running towards her, shouting something, and the wind changed direction, carrying his words toward her. "Box!"—and she finally realized what he'd been trying to tell her. Of course. Destroy the box, destroy Acosta's control over his pets. Calling upon the improbably accurate shooting skills she'd had ever since being implanted with her double's memories in the other universe, Olivia took aim and fired. She saw the box shatter on Acosta's wrist, splintering into shards. Distracted, Acosta paused, and she aimed again and fired, this time hitting him in the leg. Acosta stumbled and fell to the ground.

The bat screeched, beating its wings. Dunham felt the breeze it stirred, smelled its warm breath, rank with the blood of its victims. She closed her eyes for an second, thinking she might pass out. Then the shame of being labeled a coward by these otherworlders drove away her fear, and staring the bat straight in its eyes, she raised her weapon with hands that didn't shake at all and fired. Cut off in mid-screech, the bat exploded with a satisfying splotch sound. Dunham let out a long, sobbing breath she didn't realize she'd been holding. Shit, she thought, that was fun. Grinning, she took aim at another bat.

Olivia and Lee ran to Acosta, covering the distance in seconds. Acosta half-sat, half-lay on the tarmac, clutching his wounded leg. He stared up at Olivia in outraged disbelief.

"You broke my box," he said, indignation vying with astonishment in his voice. "You shot me."

"You won't die," said Lee. "It's only a flesh wound." He looked at Olivia. "It is, isn't it?"

She nodded. "He'll live." She knelt down to meet Acosta's eyes. "Why did you do it, Dr. Acosta? Why did you let the bats kill innocent people?"

"I had no choice." His voice was low, strained with effort. "My mother had a stroke six years ago. She never recovered. All she does is lie in a hospital bed in Mexico. She was an artist once, so full of life…do you know what it's like, Agent Dunham, to see someone you love in that state? To look in their eyes and see nothing, to realize they don't even know you? No-one should have to go through that, no-one." He drew a breath, his eyes unfocused. Olivia and Lee exchanged glances.

"I knew the answer, the cure, lay in the saliva of the vampire bat. But my research wasn't going fast enough. I needed more DSPA. Then I discovered the key to unlocking the world between the worlds. A place where every legend, every dream, every nightmare, is real. The creatures there…they're bigger. Faster, stronger than anything I'd ever seen. Perfect for my research. At first, I could control them. But they needed to feed. The bats liked this world. Plenty of…food." His voice faded to a whisper, and his eyes glazed over. "I couldn't control them any more." Acosta's eyes rolled back into his head and he slumped over, unconscious.

Everywhere, bats were dying, dropping from the sky like rain as Dunham fired, picking them off one by one with effortless ease. Astrid joined her, aiming and firing with less skill but equal determination. The screams and panic of the crowd ceased, and those passengers who hadn't already returned to the plane stood and watched this real-life video game unfold before them, their fear turning to excited interest as it became clear the worst of the danger was past.

Walter swung the heavy broadsword—stiffly at first, then with greater ease as the fencing skills he'd learned a lifetime ago at university returned to him. He thrust and parried, dancing back and forth just out of reach of the fangs and claws that threatened him. Three, four at a time, the bats dove, and every time he beat them back with expert flicks of the blade that sent them careening away through the sky, dripping black ichor, to be picked off by Agent Dunham.

"Look at the bats!" said Astrid, and Dunham, distracted for a moment from a shot, turned her attention to the ground where Agent Farnsworth was pointing. The dead and dying bats were changing before their eyes; fading, dissolving into a clear, gelatinous substance that soaked into the tarmac before disappearing altogether. In a matter of minutes it was as though they'd never existed.

"Look at Walter!" said Dunham. Surrounded by bats, Dr. Bishop whirled his sword, skewering two of the creatures and flinging them to the ground. They shuddered for a moment and then lay still. "Go, Walter!" shouted Astrid, pumping her fist in the air. Walter gave her an answering manic grin accompanied by a thumbs up before returning to battle. Only four bats left alive now, too close to Dr. Bishop to shoot safely. Dunham stayed put but kept her weapon at the ready in case one of the creatures made for open ground.

Another bat squawked and died, then another. Dunham was vaguely aware that Lee and Olivia had joined them, and that a couple of EMTs were tending to Acosta, who was down. She'd forgotten all about him. As they watched, Walter, spurred to a new fury of manic activity, slashed and thrust with all his might, and the bats, maddened with pain and the scent of blood, renewed their attack with even greater ferocity.

Then, with one last, mighty jab of the blade, it was all over. Walter let out a ringing cry of victory and stood, sword and its cargo of expiring bats held high to the heavens in triumph. The agents all ran to join him. "Walter, are you all right?" Olivia asked. Dr. Bishop looked at the assembled team, then back to the bats, impaled like some weird kind of shish-kebabs on his blade. Already they were starting to fade, dissolving into gelatinous goo that dripped onto the tarmac with a glooping noise.

"Do you suppose," Walter asked, "that Lebanese place on Winter Street does carry-out?"

The sky was starting to lighten in the east by the time the mess was cleared up, witness statements recorded, and Dr. Acosta taken away in Federal custody. The injured had been removed to local hospitals for treatment, the dead bagged, and the remaining passengers of the doomed flight to Mexico transported by shuttle to a nearby hotel. Only the four agents and Walter remained. Olivia stood by herself, hands shoved into the pockets of her raincoat, so fatigued she could barely stay upright. She was dimly aware of Agent Broyles joining her after exchanging a few words with the other members of the team. He'd arrived on the scene just as the battle ended, having flown in from New York on the Massive Dynamic helicopter as soon as he got word of Acosta's attempted flight from justice.

"Did Acosta say anything else?" she asked, blinking and trying to focus on him. It took some effort. He shook his head.

"Very little. About all we've been able to determine is that Acosta probably isn't his real name. The hospital he claimed to work for in Mexico has no record of him, but we've sent his picture and fingerprints to the authorities there, just in case something turns up. As soon as he's done being processed, I'm having him transported to Massive Dynamic. Nina is very interested in his research, and thinks she may have a position for him there."

"He was responsible for the deaths of nine people," said Agent Lee, who'd come up so quietly Olivia hadn't heard his approach. "That we know of. And injured dozens more. And you're rewarding him?"

"Nina thinks his research could save a lot more than that," said Broyles. "Sometimes we have to sacrifice our principles for the greater good, you know. And besides, I've learned that when Nina gets in one of her moods, it's best just to do as she asks." He gave a wry half-smile. "You look exhausted, agents. Go home, get some rest, take tomorrow off. You did good work tonight; you deserve a day to yourselves."

Olivia opened her mouth to thank him, then thought of something. Reaching into her pocket, she pulled out a Baggie that held scraps of what looked like black plastic and some kind of silvery metal, held together with a jumble of red and green wiring. It crackled faintly with energy as she touched it, sending off a small shower of blue sparks.

"This is what's left of the device Acosta used to control the bats," she said. "Could you have someone at Massive Dynamic take a look at it, see if it can be repaired or maybe copied? I think…" She hesitated, wondering if she ought to reveal anything about her other problem, and decided it had better wait. "I think it may be able to help someone."

Broyles raised an eyebrow at her words, but said nothing; merely nodded as he took the bag from her. Olivia was abruptly anxious to get away.

"I have to take Walter home now," she said.

"You sure?" Her boss looked doubtful. "I can have someone else do it if you're too tired."

"No, I'm good. It's on my way, anyway. Not a problem. Come on, Walter," she added as the old scientist bustled up to them, brimming with barely contained excitement. Unlike everyone else there, he looked wide awake; bright-eyed and chipper. Probably high on something, Olivia thought. "Let's get you home."

"Olivia, Agent Broyles said I can keep the sword!"

'That's great, Walter." The image of Walter dueling giant bats with a sword he'd stolen off a dead man was one she didn't think would go away any time soon. "We've just been discussing Dr. Acosta."

"Did he dissolve into goo too?" Walter looked quite cheered at the thought.

"Nothing so dramatic," said Broyles. "He's in a holding cell, pending transfer to Massive Dynamic. Nina may have some work for him." They went to collect the other agents, and together, they all made their way to the parking lot and a row of utilitarian black SUVs, their government issue rides. Astrid offered Agent Lee a lift home, as the apartment he rented near MIT was on the way to her own place in Cambridge. Meanwhile, Dunham arranged to hitch a ride back to New York and the Bridge Room in the MD helicopter.

Olivia played Amherst NPR softly on the car radio on the way home, the early morning jazz program helping to keep her awake and focused on the road. Walter was quiet—uncharacteristically so—and she thought a few times he'd fallen asleep, but every so often he'd surprise her with some unexpected non-sequitur. The sun had just begun to peek over the horizon as they pulled up across the street from the big Victorian house Walter lived in, courtesy of Harvard and the FBI. The wide, tree-lined street was quiet except for a paper boy on a bike tossing papers onto front porches and an elderly woman in a flowered housecoat letting out a dog. The rain and humidity had finally cleared out, leaving the sky free of clouds and the city cool and refreshed.

Sunrise had always been Olivia's favorite time of day, so full of promise. She slowed the SUV, enjoying the way the warm golden light played over the landscape and onto her tired face. Then the light flickered and went blue, and she swerved onto the sidewalk and jammed on the brakes to avoid hitting the guy who stood there, right in the middle of the street. His hands were thrust into the pockets of his pea jacket, and his eyes met hers in a knowing gaze, but he didn't seem to notice the flock of sparrows that flew through his head on their way to a neighboring feeder.

Walter lost his grip on his case, which landed on his foot with a thud. He sat up with a muffled curse as Olivia backed off the sidewalk, executed a neat U-turn and maneuvered back down the the street, scanning for a parking space close to his front door. Too late to hope he hadn't noticed anything strange about her driving, but maybe he'd just put it down to fatigue.

"Sorry about that," she muttered. "Swerved to miss a squirrel."

"Admirable," replied Walter, "but I would have been more concerned about the man in the road, myself."

Olivia slammed her foot down on the brake, jerking the SUV to a screeching halt and sending accumulated objects flying. "You…" she began, and stopped. Swallowed, gripped the steering wheel hard to keep her hands from shaking. "You're telling me you can see him?"

"Oh, yes. For several days now. It began right about the time I found this," and he reached into his pocket and produced a round silver disc, darkened with age. He held it up to the light so that she might see better. "It's an old half-dollar coin called a Walking Liberty. Quite valuable, as I understand, though I was never a coin collector myself. Belly dabbled in it at one time, but then, he collected all manner of things." He frowned, as if trying to recall something. "It's…important, I think, but I can't remember why."

"It's about that man, isn't it?" Olivia looked up to where the man had been standing, but he was gone again. "Something's happening, something I can't explain. I found a book in my apartment that shouldn't be there. And for days now, I've had this feeling that I ought to remember something, but I can't." Foremost in her mind was overwhelming relief—Walter sees him too, I'm not crazy—and then it occurred to her that that might be somewhat counterintuitive, to say the least. What's that word for when two people share the same psychosis?

"Folie á deux," said Walter, as if reading her thoughts. "Interesting that you're seeing him as well, my dear, but if this is madness, it's taking a very specific form, don't you think? No apparent pattern to the—the manifestations, if I may so describe them; no trigger events. A seemingly random phenomenon, and yet…we're both nagged by the same feeling of loss, of an event or person we need to remember, but cannot. Fascinating, and maddening."

"Walter." Olivia turned to him, her voice urgent. "I think he comes from the same place as the bats. He and Acosta both used the same words to describe it: a place where nightmares are real. I think he's trapped there, between the worlds, and he needs me—us—to help him find the way out. He and Acosta both mentioned a key…Walter?" She looked anxiously at him. Dr. Bishop was staring out the windshield at nothing, his eyes unfocused, lips moving silently. He seemed to have forgotten she was there.

"Walter, do you know who this man is?"

He took a long time to reply, as if calling up an answer from the utmost depths of his fractured mind. "Perhaps memory is the key," he said at last, his voice so quiet Olivia could barely hear him. "Yours, and mine, but especially yours, given the unique properties of your brain chemistry." He gave a long sigh, looking suddenly much older than his years. "I think…I think his name is Peter."

"Peter." Why did that name bring a rush of emotion, of feelings so powerful, so overwhelming she could barely contain them? Random pictures flooded her mind; memories that could not possibly be hers, and yet…

Walter had fallen silent again. It was as if his thoughts had turned inward; gone to a place only he could see, a place deep in his mind. Finally he turned toward her, and Olivia caught her breath as she saw in the old man's eyes, unfocused and half-mad, something she had not seen there in a very long time. Hope.

"He's my son."

THE END