Stumble along in the dark. Fall to the ground, knees weak, stomach involuntarily emptying itself.

Hangover.

Still night. Everything was dark. Charlie couldn't see a thing around him. There were only two things that he could distinguish: that he was staggering along uneven ground, and that Don's arm was supporting him.

What had happened? Charlie had never had a hangover like this. And in front of a group of fellow academicians, his peers? That was beyond belief—

Not Don. It wasn't Don whose hand was gripping him, keeping him moving. And it wasn't night, either—it was a blindfold. Icy fear swept through his veins.

It all came back in a rush: the lecture. The post-lecture discussion. Waiting for Penfield to walk into the salon, because then the real debate would begin, and Charlie had already prepared a whole bunch of pithy comments based on Penfield's last three articles that he was eager to use. Then…Charlie had fallen asleep. They'd all fallen asleep.

The probability that every one of the mathematicians in the salon would fall asleep after a highly stimulating lecture without the benefit of a nearby bed was so remote as to be unthinkable. No, wait; it was after Penfield's lecture. Boredom needed to be factored into the equation. Charlie irritably revised his estimate upward, and decided that the difference still wouldn't achieve statistical significance. That just didn't happen without some sort of activity that was more in keeping with Don's lifestyle than Charlie's.

All of which meant that he was in serious trouble.

He stumbled again, and the strong hand hoisted him up. A step, Charlie determined, a single step upward, into some sort of building. He heard a mumble from behind him, and realized that there was someone else in a similar situation as himself, someone feeling just as bad as he and who had stumbled over the same step to enter the same place. Who was it? A reasonable supposition was that it was someone else from the salon, but from there Charlie had no idea. There were many people present who were brilliant in the field of mathematics, but once again it came back to the reality of how math was perceived in the world: a useful tool, and that was about it. Not like physics: atomic bombs, and others things that went boom. Not like chemistry: mad scientists with miracle potions and drugs. Not even biology and medicine, to weaponize the bacteria of choice. Why the heck had these people gone after mathematicians?

He was about to find out. His knees gave out once again, only this time the hand pushed him onto something soft, something sofa-like. His grunt was muffled into the gag in his mouth, but the hand then relieved him of that burden by ripping the duct tape off of his skin.

The scream of pain left him before Charlie even realized it, and he suddenly understood what Don had been talking about a few months ago after an undercover case. Duct tape, removed swiftly and without mercy, hurt like hell. A second screech, echo-located somewhere off to his right, suggested that his fellow math victim had suffered the same fate.

The blindfold was next. Charlie blinked, trying to see through the tears of pain. He was in a large drawing room, with elegant upholstered furniture all around. He himself was sprawled over a green brocade sofa, warm mahogany wooden feet sticking out for support to keep the brocade off of the beige plush carpet. He glanced automatically toward the windows, hoping to gain some thoughts as to where he was or even what time it was, but heavy velvet drapes prevented the passage of photons or information.

There were three men and a woman, all of whom were watching Charlie and his fellow victim. Charlie recognized none of them, but suspected the men, at least, of being responsible for his abduction. They each had the hard look of men who were well accustomed to performing reprehensible deeds as a matter of course, and receiving premium pay for such actions. They were the hired help, but they were upper level hired help.

The woman was different. She was the one doing the hiring. She was no spring chicken, but the signs of aging had been systematically purged through the judicious application of time and money and surgery. Every hair was lacquered into place until nothing moved unless she gave it permission. Charlie guessed that she was the one who had arranged for the abduction.

Charlie's fellow victim cleared his throat, and Charlie automatically glanced at him. Who was the fellow? Charlie didn't recognize him, and he knew by sight just about everyone who was anyone in the field of theoretical math. The man was taller than either himself or Don, with light brown hair slicked back. He had the same look as many of Charlie's own colleagues, the look that said searching for elucidation was a valid way to conduct one's life, and that the search could be conducted in a reasonably intellectual fashion.

There the similarity ended. Charlie was well aware that many of Charlie's fellow professors had a somewhat head in the clouds approach to living—Charlie, of course, was far better grounded, no matter what either Don or his father said!—but this man seemed far more practical than most. Even flopped over the easy chair, the limbs still seemed more composed than Charlie's own.

The woman interrupted Charlie's musings. She rose from her chair, standing over him. "Professor Eppes. Professor Penfield. Welcome to your new digs."

Penfield? What was she talking about? That man wasn't—Charlie caught the look the man gave him. There was nothing there, not a hint that the man wasn't Marshall Penfield. If Charlie hadn't verbally sparred with the man during both undergraduate and graduate years and beyond, he could easily have believed that the angry visage across the room belonged to his nemesis.

Play it cool. Was the man undercover? Don didn't talk much about those sorts of things, but this could be one of them. Charlie was well aware that his own brain wasn't functioning particularly well, still trying to swim up out of a drug-induced fog, and elected on the spot to keep quiet until he had the opportunity to clear things up. The wrong thing said at the wrong time could easily end up with a dead mathematician, and he wasn't talking about the imposter on the easy chair.

Charlie cleared his throat, but nothing came out.

The other man managed the process better. "What do you want with us?" A simple question, evoking so many emotions; Charlie found himself holding his breath.

The woman nodded. "Quite simply, Dr. Penfield: you have a new employer."

Charlie tried to match the other man's composure. "You?" It would have come out better, Charlie decided unhappily, if his voice hadn't squeaked.

She spared him a pitying look. "Yes, Dr. Eppes, that would be correct. You may refer to me as Ms. Marple."

'Dr. Penfield' drew the attention back to himself. "What if we don't want to work for you?"

"I think you'll find the terms of employment far better than the alternative, Dr. Penfield."

"And that alternative being—?" 'Penfield' lifted one eyebrow in a way that reminded Charlie of the real Marshall Penfield, with that mildly supercilious air, as though he considered himself superior to everyone—including Charlie himself.

Return smile. "We will kill you."

"Oh." 'Penfield' took in a short breath, and paled. "Oh, I see."

Charlie tried again. "What do you want us to do?"

"The same thing that the NSA has asked you to do: encryption work. You will work here, in this house. You will not leave this house. You will not attempt to contact anyone. You will decipher any message that we give to you, without complaint and without stopping. In return, you will be well-treated. You will be fed and sheltered."

"But we can't leave." 'Penfield' took care of the responses.

"Just so. Any attempt to contact anyone outside of this house will be punished swiftly and thoroughly. Do I make myself clear?"

"But we have to—" Charlie started to say.

'Penfield' overrode him. He rose from his chair, an expression of anger on his face. "This is intolerable! I have classes to teach! You can't simply abduct—"

It happened so fast that Charlie almost missed it. Ms. Marple made a small gesture to her men.

There was a flurry of fists as the three men descended onto 'Professor Penfield'. A short series of thuds, interspersed with cries, emerged from the pile-up. "Stop! Stop! I'll do it!" he cried out.

"Stop it! You're killing him!" Charlie yelled, starting to get up himself.

"Do not interfere, Dr. Eppes," she snapped, holding him in place with a single upraised finger. "Not unless you wish the same treatment."

It wasn't hard to tell that the team from NCIS that Fornell called earlier had arrived at the hotel. There was no siren, but the screeching tires could be heard even inside where Don and his own people were milling around. Likewise, it wasn't hard to pick out the three agents steaming across the hotel lobby toward the salon where the math debate had come to a snoring halt.

Don studied the trio during the few seconds he was given before their arrival. Their leader was a silver-haired man, but that was the only apparent sign of age. He moved like an athlete—not that Don was surprised, not for a Federal field agent—and possessed long legs that ate up the distance between the front lobby and their destination where the FBI waited for them. The other man of the group was just as tall, with a tailored look that said the man cared thoroughly about the image that he presented to the world. Don tightened his lips; a dilettante, playing at being a cop? Took a job that gave him an excuse to spend time working out and admiring himself? Don didn't have time for this sort of nonsense, and nor did he have time to waste coddling the smaller woman stretching her legs to keep up with her tall companions. Attractive enough, sure, but at the moment Don was more concerned with their ability to find a certain world class mathematician. If he needed her to go undercover, he would ask, but right now he needed brain power and muscles. He sure hoped she could contribute the former, because the latter wasn't likely. Not with those slender curves.

Fornell recognized them, and moved in on the introduction. "Gibbs. Eppes, an FBI SAC for L.A. He's here doing a lecture."

"Yeah?" There was a world of interrogation in the single word, something along the lines of what the hell is an ivory tower lecturer doing out where he could get hurt, because he sure can't help the investigation.

"Eppes's brother is one of the kidnap victims, Jethro," Fornell said with a faint air of reproof.

Don didn't have time for a turf war. "What was your man doing here?" he asked evenly, trying to keep his own temper under control. "You have an undercover going down?"

"Not me, Eppes. Your brother? He something special?"

"Yeah." Don chose to drop a few names—letters, actually. Initials. "Top notch mathematician. He's done a fair amount of work for the NSA, the FBI, the Pentagon; places like that." He let the words drop into the empty air.

The NCIS woman cocked her head. "Your brother is Professor Charles Eppes?"

Brains, then. Don nodded. "That's him."

She had an accent. Don wasn't quite able to place it, wondered what someone who wasn't an American citizen was doing in an NCIS unit. She turned to Gibbs. "Dr. Eppes is well-known to us. His work is greatly admired." She paused, thinking. "Gibbs, there could be a connection. Dr. Charles Eppes is one of the premier names in crypto-analysis."

Okay, she got another point for flattery, but that didn't help to find Charlie. Don moved on. "What connection?" He turned to stare at Fornell. "Is this the missing message thing that half the agents in town were talking about earlier?"

"It could be," Gibbs forestalled Fornell. "We picked up a call a couple of hours earlier. One of the low levels was calling some potential buyers, trying to arrange an auction."

"Bring him in," Don ordered. "Let's question him."

Gibbs shook his head. "Can't, Agent Eppes."

"Why the hell not?"

"He's dead."

McGee saw it coming, saw Professor Eppes start to agitate his new employer.

The woman—Ms. Marple, she stylized herself—had just finished explaining their new conditions of employment. "Just so. Any attempt to contact anyone outside of this house will be punished swiftly and thoroughly. Do I make myself clear?"

"But we have to—" Professor Eppes started to say, raising his voice.

'Penfield' quickly overrode him. McGee rose from his chair, placing an expression of anger on his face. "This is intolerable! I have classes to teach! You can't simply abduct—"

It worked. The group focused their displeasure on him, with their fists.

The first set of knuckles smashed into his mouth, and McGee concentrated on acting like a milquetoast college professor. He cried out, trying to back away, finding that it didn't take much acting ability to make it sound real.

They didn't let him escape his punishment. One grabbed his arms, and the other two rained blows onto whatever was closest.

That didn't matter. He had diverted them from delivering this beating to Dr. Eppes, prevented them from possibly permanently damaging the mind of one of the world's greats. Special Agent Timothy McGee would receive thanks for this from the academic and political worlds, if he lived through this slice of life.

Don let himself be mollified by the speed and skill that the NCIS team showed in processing the scene. They knew their business, that was clear. The man—DiNozzo was his name—snapped pictures of every corner of the room, and the woman had pulled on latex gloves to track down every stray hair that might lead them to the kidnappers.

Gibbs examined the wallet with the gold shield, using his own gloves to avoid leaving prints. "That's McGee's," he confirmed.

Sinclair narrowed his eyes. "What was your man doing here?"

"Up here, in this room, apparently getting himself kidnapped." The NCIS team leader refused to allow himself to be ruffled. "Downstairs, in the conference room, attending a lecture on math."

"He was attending one of Charlie's lectures?" Colby's voice held more than a smidgeon of disbelief.

"Yeah. Pitiful, isn't it?" DiNozzo asked, snapping another shot. "Friday night, and all McGeek can do is get himself snatched. Although he did say he was meeting a woman," he added thoughtfully. "Someone he met online." The sarcastic humor was ruined by the undertone of worry.

Ziva bagged a sliver of glass that she found on the table in the corner of the room, carefully sealing the plastic so that the tiny shard couldn't escape. "Special Agent McGee has expertise in computer science," she explained. "He was looking forward to the intellectual stimulation."

"Right up Charlie's alley," Sinclair mused, almost to himself. "But what was he doing downstairs, in the salon? I thought only an invited few would be there. Would your man be of that caliber, to be invited?"

Gibbs heard that, and shook his head. "McGee is good, don't doubt that," he equivocated, "but he stays out of the limelight."

"Besides," Ziva added, "this was a lecture on mathematics, not computer science."

"There's a difference?" Colby asked.

"A big difference," Ziva assured him.

"What is it?"

"Got a couple years?" DiNozzo put in, "'cause it'll take that long for your guy and ours to explain it to you."

Colby grimaced. "I can believe that. I've heard some pretty wild math fights. Never knew that math guys could be so ferocious until I met Charlie."

Gibbs changed the subject. "Anybody talk to the help?"

"It was the doorman," Fornell told him. "He was one of them, but didn't know what he was doing. Didn't see anything."

"He see McGee walk in?"

Fornell blinked. "He must have."

"Really? He was supposed to have let that other math guy in, named of Penfield." Gibbs smelled blood. "I think I'll have a little talk with him."

"But, mom, I don't wanna go to school."

It must have been that Toby West kid. Him and all his friends. They caught him—again—and took his lunch money and his homework. Timmy had been able to hide the bruises from his parents, 'cause telling on Toby would just make Timmy look like a wimp. It would also get Toby in trouble in school, and that would mean…

Crap.

Reality crashed over him with all the delicacy of an ice shelf breaking free from the Antarctic. He wasn't ten years old again, trying to survive elementary school as a budding geek. It wasn't anyone as impotent as Toby West—he'd heard that Toby had done time for selling drugs, right after he got out of high school. Served him right—and these bruises were a sight worse than anything Toby had ever doled out. No, at the moment he was lying on something soft with every inch of him trying to decide whether 'sore' could be the correct adjective or whether they'd be more accurate with 'excruciating discomfort'. At least it wasn't 'agony', he decided.

"Are you all right?"

McGee swallowed—even that hurt. "Yeah," he croaked. He coughed, wincing, and tried again. "Yeah," he repeated, morbidly pleased that this time it sounded like an actual word. "Yeah, it wasn't too bad," he said, lying through his teeth.

"Let me help you sit up." Strong hands slid under his shoulders, helping McGee to move into a sitting position, pushing soft pillows behind his back for support.

McGee let his head fall back against the cushioning, discovering that he had been deposited onto one of the sofas in the living room of the house that they'd been stashed in.

It wasn't as bad as he'd feared. This wasn't some sort of dirty safe house, cockroaches demanding equal time from the rats and shards of pizza crusts hanging out from dilapidated cardboard boxes. The place looked livable; in fact, it looked almost as inviting as McGee's own place. No, actually, it looked better because someone had gotten around to dusting the place, something that McGee had been putting off in favor of solving the last case and avoiding the boss's head-whacks.

"Thanks."

McGee blinked. "You're welcome." The words emerged automatically, and he suddenly realized who he was speaking to. "Uh, Professor Eppes…"

"We know who I am," Charlie said dryly, "so shall we establish who you are? Trust me on this: I know Marshall Penfield on a first name basis."

"Yes, well…" McGee let the words trail off, trying to pull together his thoughts. "I, uh, I picked up Professor Penfield's ID badge. It must have fallen off, and he didn't realize it. I went to return it, and…" More trailing words.

Charlie nodded, considering. "I can see how that could have happened. You don't really look alike, but those photos are pretty blurry."

McGee breathed a sigh of relief. "You believe me."

Charlie dashed his hopes. "Let's just say that I don't have any reason not to, as of yet. What were you doing in a private discussion?"

McGee had always believed that honesty was the best policy. "I was here to hear your lecture," he said simply. "The rest…well, it just happened."

"Right." Charlie sat back in the over-stuffed chair facing him. "So, who are you?"

"Tim McGee," McGee told him.

"That's a start."

McGee's smile needed help. "Special Agent Timothy McGee, NCIS."

"NCIS?" It was Charlie's turn to blink. "As in Naval Criminal—?"

"—Investigations Unit, yes," McGee finished up for him, briefly amazed that someone had actually heard of the department before remembering for whom Professor Eppes had worked.

"Special Agent," Charlie mused. "Field agent?"

McGee couldn't blame the math professor for the doubting note in his voice. It wasn't as though Charles Eppes, one of the top mathematicians in the world if not the century, was seeing one Special Agent Timothy McGee at his best. Staring at Dr. Eppes, that master's degree from MIT that so impressed DiNozzo (even if the man wouldn't admit it) and that McGee had worked so hard for seemed something less than the achievement that it was. "Yes."

"All right." Charlie paused, thinking. "Well, you've carried off the fake so far, and I don't see any benefit to admitting your real identity."

"Thanks."

"You're welcome. Do you have a plan to get us out of this? Alive would be preferable."

McGee winced, and it wasn't all from the bruises. He briefly considered lying. "No. You?"

"They want us to decipher a coded message," Charlie told him. "In fact, it's their new business, with Penfield and I as their hired help at rock bottom consulting fees."

The plot started to become clear to his battered wits. "They kidnapped us, intending to keep us working for them. Decryption analysts, for whoever can pay but doesn't have the backing of a legitimate government." McGee forced his befuddled mind to work. "Not a bad scheme. There would be a market for something like that, assuming that they can get us to cooperate."

Charlie indicated the darkening bruise that threatened to close McGee's eye altogether. "They've made a good start."

McGee touched the spot, and hastily pulled his hand away. "Yeah." He turned his attention to his new-found fellow employee. "Have they hurt you?"

"No," Charlie told him. "They seem to think that I'd be impressed with what they did to you. I was," he added grimly. "I'm going to do my best to avoid ending up in the same condition. Thanks, by the way. I realized too late what we had gotten into. I owe you one. It should have been me lying on the sofa with all the bruises. They intended to make an example of one of us, and I was walking right into their trap."

"Dr. Eppes," McGee told him with all sincerity, "you are one of the greatest minds in the world. I couldn't allow you to be hurt."

Charlie flushed, embarrassed, and hurried on. "Yes, well, let's see if we can't avoid that for both of us from here on." He changed the subject. "They've handed me the first message that they want deciphered. It'll take a while, especially with the dinky little computers they've allowed, but I can do it. What we need to do is teach you some phrases to parrot back at me, so we can make it look like you really are Marshall Penfield. Let's start with—"

"I'm going to assume that we won't have anything as simple as substitutions or blocks," McGee interrupted. "Multiple keys? Public and concealed?"

Charlie's face took on a pleased expression. "They teach ciphering techniques in NCIS school?"

"Not exactly. I did a little work in it during my undergraduate years, and more later on, at MIT."

Bigger grin. "Ever run across a guy by the name of Nadir Samrahi?"

McGee's jaw caught itself in the nick of time to prevent hitting the floor. "Uh, you mean, Professor Sammy? He was doing work on adapting the asynchronous deciphering algorithms for use directly on the Linux platform, without needing to go through any intermediaries."

"Was he successful?"

McGee looked blank. "I don't know. I graduated and moved on, and got involved with other types of work. I never heard anything more." The blank look extended itself. "I would have thought that I would have. Heard, I mean. I went straight to work for NCIS, doing work in cyber-crime, and while it wasn't directly involved, I would have thought—"

"He gave it up as a bad job," Charlie interrupted. "Good idea, but failed in execution. Sammy found that there were easier ways to accomplish the same thing." He nodded. "We can pull this off. Penfield always hated the part about transferring the work onto the computer for cranking out the calculations, but hopefully our friends outside this room won't know that. I'll put the algorithms onto a white board—" he looked around for the missing piece of furniture and corrected himself, "onto paper and you'll handle writing code."

"In the mean time," McGee agreed, "we can watch for a way to escape."

"Well, duh." Abby stared at the tiny sliver of glass bagged in transparent plastic. "Of course I can figure out what the liquid is. Put it over there," she directed DiNozzo, "onto the bench. I'll get to it after I finishing running the slug you guys brought me from earlier. I'm only one person, you know."

Abby Scuitto was not like any other forensics rat that Don Eppes had ever seen, and he'd seen his share of them including the over the top strange ones. He really hoped that she was competent, and right now he likewise hoped that appearances were deceiving. Black hair, pale skin, and goth-child awkwardness didn't usually go hand and hand with technical expertise. Even Larry Fleinhardt, with all of his idiosyncrasies, could pass for normal under average circumstances.

Sure, the equipment was here, machines with lights blinking like a Christmas tree display on Black Friday after Thanksgiving, but did this chick know how to use them? Don had been in Larry's physics lab on a few occasions and this looked something like it, but Larry tended to dance from machine to machine. Even Charlie, when he performed his demonstrations for his classes, simply dove onto his devices like a drowning man onto a life preserver. This chick merely looked distracted—or was it overwhelmed? A quick glance at Colby said that his team mate shared his concern. I've got a missing brother. I don't have time for playing nice.

The NCIS team, in the persons of Special Agent DiNozzo and Officer David, didn't seem to be bothered. Don supposed that it could be because they were so used to the lack of evidence to build a case that they didn't even realize that there would be a difference. This was, after all, NCIS. Great guys, but with a budget less than ten percent of what the FBI commanded and the limited manpower that it allowed. Still, it was what they had to work with, and this NCIS team would have a lot of motivation since it was their man who had been snatched along with Charlie. I hope they liked the guy, and don't want to see him go down.

DiNozzo tossed an uneasy glance toward Don, as if he'd read the senior FBI agent's thoughts. "Abby, uh, can you, like run things together? Simultaneously? This one's a rush job."

"Aren't they all?" Goth-child took the bag from DiNozzo's hand and lifted it up into the air to stare at it. "Not much there. It'll take a while. I'll need to find a good diluent to pry it off of the glass—this is from an ampule, right?—and once I get it off the glass, then I can run it through the mass spec."

"Uh, Abbs?" Another almost furtive look, not quite meeting Don's eyes and not meeting his partner's eyes either. "Abby, Gibbs needs this fast."

What the hell was this goof-ball thinking? Tell the damn lab rat to get her ass off of her bench and run the damn tests!

"Tony, you can't rush this stuff." Abby flounced over to one of her 'toys'. "Tell Gibbs that he'll have the evidence when it's ready. He knows that."

"Abby…" the Mossad officer seemed equally as uneasy as her American partner.

"What?" The Goth-child's sentence started out annoyed—and mutated. Abby turned around and frowned. "Ziva, what's going on?" She scanned the group, looking at individuals. "Tony, why does Gibbs need this fast?" She catalogued each of the persons in her lab, noting which ones she knew and didn't know—and who wasn't there. "Tony, where's McGee? He's with Gibbs, right? Interrogation?"

Crap. She doesn't know.

"Abby…" Ziva let the word float away, not certain of what to say next.

The lab rat focused on Don as the unknown and most likely to tell her what she dreaded. "What's going on here, Mr. FBI guy? Where's McGee?"

Clearly used to getting coddled. Don didn't have time for this. "Your man and my consultant were kidnapped from a math lecture," he told her curtly. He indicated the shard of amber glass that she held in her hand, still securely bagged. "That liquid may give us a clue as to how it was done."

"And where they're holding McGee, Abby," Ziva added gently.

Tears filled big brown eyes, and Don felt like a heel. It didn't matter whether or not this kid knew what she was doing in a lab; she cared about her team and was genuinely upset that Gibbs's man was among the missing. Don didn't have to come down that hard—well, maybe he did. He needed evidence, and he needed it now.

Goth-child turned back to DiNozzo. "Tony?"

"We'll get him back, Abbs," DiNozzo promised earnestly. He steered her toward the bagged shard of glass ampule. "We think this may have been used, might have been something to keep the victims quiet. Figure it out, and it will give us a lead."

"You'll have it," Abby promised, and Don noticed those tears threatening to leak down her cheeks. She turned to her army of machines, new steel in her spine. "You heard him, men! Get to work!"

I hope that Gibbs is better at interrogation than what I'm seeing here. Don exchanged glances with Colby, already wondering how to best toss this town that they were visiting. They didn't know the streets here, or the local underground, or who might have a lead on who had kidnapped Charlie and the NCIS guy.

On the other hand, the NCIS people didn't seem to be much better off.

Not much of a consolation.