Dr. Larry Fleinhardt shook his head, perplexed. He stared at the white board, hoping for divine inspiration because mundane human thought wasn't good enough. "I'm sorry, Don. I can't help you. I wish I could."

"What do you mean, you can't help me? You work with Charlie, you speak the same language that he does." Don was working hard to keep his tension from exploding. He had dragged Charlie's colleague and former mentor to the garage where Charlie did his work in desperation. It was as messy as it had always been, dust twirling up in small dust devils as the group tip-toed through the debris. Larry held a handkerchief to his nose and sneezed.

"Bless you."

"Thank you. I work with him, but we do not, and let me stress not, speak the same language. I am a physicist, and we use numbers as symbols to describe the physical phenomena that we observe in the universe. Your brother is a mathematician, someone who can manipulate those symbols to describe and then predict outcomes that elude ordinary man. I can no more understand this equation of his than I could understand Lithuanian. He makes symbolic leaps of mathematical blind faith that baffle me. Amita?" Dr. Fleinhardt turned to the young girl beside him.

But she too shook her head. "I can't keep up either. I comprehend parts of it, but I get lost here"—she pointed—"and here,"—she pointed again— "and here,"—a third poke at the scribblings on the white board. She looked at the team from the FBI with a sheepish look. "Shall I go on? There are several more places where Charlie makes a leap of logic that I can't follow. I can get it when he explains it to me, but I have to be honest: he leaves me in the dust." She grimaced, taking in the surroundings. "Literally."

"So you're telling us that you can't tell anything about where this bitch might be hiding Charlie?" Colby said, voicing Don's despair. "This equation doesn't mean anything?"

"Oh, it means plenty," Dr. Fleinhardt assured him. "But then, so does the Rosetta Stone. Egyptian hieroglyphs. Ancient Sanskrit. Church Latin. If you can understand them, they'll tell you plenty."

"Hey, I studied Latin in high school."

"Do you still understand it?"

"I can say 'E Pluribus Unum' with the best of 'em," Colby admitted. "After that, I fall down."

"Then you see my point." Larry thought better of resting his backside against a convenient piece of wood. Several splinters to either side convinced him that discretion was the better part of valor.

"So we need a translator," Don decided. "Who's a good enough mathematician to make sense of this? Somebody at Princeton? MIT? Stanford? Oxford, maybe?"

"Without reference points, it would take days if not weeks to decipher what Charlie had figured out," Amita said. "But Don, I think that you don't need this equation. I don't think it will help you."

"Why not? Charlie was able to predict where this chick would send her goons. We picked them up. He was right."

"Because he was trying to determine the most likely probability of a location for a robbery," Amita explained. "He factored that into the equation. I recognize some of the location variables. Here, this numerical phrase and this one: those are used to rule out some of the less likely possibilities. And it looks like he was able to successfully incorporate some of the personality dimensions. He must have listened to what you had to say, Megan."

"Nice to know that someone does." The humor fell flat. The situation didn't support it.

Amita went on. "But this equation is unlikely to predict a location for this woman has gone to. It looks for crime sites. This woman is in a place where she can hide Charlie." Or Charlie's body, went unsaid. Perhaps the graduate student hadn't thought of that angle. Every FBI agent present wished that they didn't have to.

"So, bottom line," Don said grimly, "is that we're clueless."

"Did you enjoy humiliating me?"

For the life of him, Charlie couldn't figure out what this woman in front of him was talking about. Of course, trying to think when his leg was throbbing, his head playing the 1812 Overture in cut time, and his shoulders in the process of being ripped out of their sockets by the ropes stringing him up to the rafters didn't help matters. Is this what Don put up with in his job, the parts that he wouldn't talk about? His admiration for his brother rose substantially.

The trip to here, where ever here was, was mercifully blurred. It took, he estimated, some thirty minutes to get here. The actual number, he calculated, was between 41.93 and 20.97 minutes. There had been 2516 heartbeats during the time he was in the trunk of her car, and, assuming that the average heart beat 60 to 100 times per minute, and that his might have exceeded that number on occasion due to the roughness of the ride…Numbers were always better to work with.

She slapped him. "Pay attention!"

Charlie blinked. It was getting harder and harder to concentrate. "What did you say?"

"I said," and she stuck her face close to his, "did you enjoy humiliating me?"

What was she talking about? Charlie took a stab at it, hoping to say the right thing. "Actually, I found it very difficult to predict where you would strike next. The equation was extensive. I had to test some very questionable hypotheses. Most of them didn't work."

She stared at him. "You're an idiot. You really don't know who I am."

Confusion, this time. "Have I met you?"

"Yes, you have, Professor Eppes." She drawled out the title as an insult. "You flunked me."

"Oh." Charlie really didn't recognize her. She was tall and blonde, lots of leg with a hard look to her, the type to stand out in a crowd as someone who could sleep their way to the top of the Hollywood sleaze list. It had to have been his freshman class. There could easily be two hundred students in the lecture hall, and he'd taught that class for the last few years. It was only his upper level classes where the numbers dwindled down to a recognizable few and he'd learn names, and most of the students at that level tended not to fail. Some of the freshmen came to see him, to talk and to learn, but the majority simply wandered off to their next class… What should he say next? What could he say to a former and disappointed student? "I'm sorry."

"Oh, I think you're going to be a lot more than sorry," she said cryptically. "Want to listen when I call your brother?"

"My brother?" Charlie hated it when he couldn't think straight. It had happened once before; he had had the flu, and a fever, and he'd let himself get run down working out that problem based on Wernicke's Theorum—

Whack!

He saw stars. He tasted blood on his lip. "Stop that," he said irritably. Can't make things worse now, can we?

Yes, we can. "Know what this is?" she asked conversationally, holding up a long piece of metal with two prongs on the end it.

I don't think I want to know.

"Yes, you do," which is how Charlie realized that he'd actually spoken aloud. She casually rammed it into his side and squeezed the trigger. Fire dripped through him, sending him reeling and an unannounced scream echoing through the rafters.

His kidnapper only laughed. "Yeah, that's kind of how I felt when I saw my final grade posted. Let's go call your brother."

He didn't want to answer the phone. He really didn't want to answer the phone. What Don Eppes wanted to do was to crawl under a rock somewhere and pretend that this whole case wasn't happening. How could everything have gone so wrong? Worse; how could he face his father? Could Don get away with sending someone else to pick up the man from the hospital tonight?

No. No matter what, Don would face this with his father, shoulder to shoulder. His father wouldn't blame him—well, maybe he would. Charlie wouldn't have gotten involved with the FBI if it weren't for him. The NSA was another story, but the NSA hadn't gotten Charlie kidnapped by a crazy bitch who liked to send out cryptic messages. According to Charlie, the NSA had kept him safely locked up in a little office with a white board and a computer until he was ready to come out with the answer. The FBI had turned out to be a little more immediate, a little more hands on. A little more danger.

And he damn well didn't feel like answering the phone. Little bitch hadn't called them for the last caper, just sent her people out. In a snit, she was; all pissy because Don hadn't let her talk directly to Charlie. But it could be her, with her computer-generated voice to cover her real identity. A ploy to throw them off the track. It had worked, for a while. Then Charlie questioned the assumptions. And Megan questioned the assumptions. And then the FBI reeled in the three expendable crewmen by out-thinking their bitchy boss. Little Miss Cipher was now out there all on her own. No henchmen; that ought to tick her off. Ticked her off enough to snatch Charlie.

He supposed he ought to answer it. Colby was out there, tracking down the components to the gas and the tubing that the bitch had used to pipe in the gas in Charlie's house. It might be a clue.

It was better than that.

"Eppes."

"Too bad I can't talk to your brother," said a husky female voice. "Oh, wait. I can. He's right here."

Don's lethargy vanished in a split second. He snapped his fingers frantically at David: get the tracer going now! David all but vaulted his own desk in a race to beat time itself in starting the equipment. He pounded on the buttons, twisted the dial, and stared at the readings, willing the information to arrive. It would take valuable minutes. He nodded at Don: working. Keep her talking. Keep the connection live. Megan sidled up to Don, quiet, adding non-verbal support.

Don put it on speaker phone, so that the rest of his team could hear, could give him silent and immediate feedback. David was shaking his head, watching the timer on his board: not yet. Need more time.

"Let me talk to him," Don demanded. Rule One in the FBI manual on kidnapping negotiations: make sure the kidnappee is still actually in the kidnapper's possession. And alive. Preferably both.

"No, I don't think so," she replied thoughtfully. Taunting. Teasing. Her own voice, not the computer generated nonsense. Maybe she left that equipment in another abandoned hideout…

"How do I know that you have him?" Charlie's smart; he could have escaped…

"Oh, I've got him. You know that very well, Special Agent Eppes."

"Prove it."

"You really want me to, Donnie boy?" More taunting, this time with more bite to it.

Don raised his eyebrows at Megan, alarmed. Do I push?

Megan didn't know. She lifted her shoulders helplessly. There was a threat in the woman's words, but what that threat was, Megan had no idea. The FBI rule book didn't cover this part.

How much longer? Don mouthed at David.

Another unhelpful shrug from a team member. Maybe sixty seconds? Ninety?

Don bit his lip. "Let me talk to him," he told the handset, astounded at how steady he was keeping his voice. You're a damn fine agent, Special Agent Eppes. Are you good enough to keep your brother alive? "I need proof that he's still breathing."

"We all have needs, Donnie boy. You haven't asked me what mine are yet."

"What are your needs?" he asked obediently. Across the table David nodded. Keep her talking. Almost there.

"I need a million dollars, in small unmarked bills. I need free passage out of the country."

"It'll take time."

"Better not take too much time. In fact, it had better not take beyond four o'clock today. I've got your brother here. He might not be a very happy camper if you make me wait too long."

Push, Megan inserted. Nothing to lose on this point.

"We haven't established that fact yet," Don told the phone. "Let me talk to him. Prove that you've got him."

"Okay. I guess he's earned this," she said cryptically. "Professor Eppes, your brother wants to hear from you." They heard some rustling, the sound of footsteps as shoes approached the victim.

"Don?" Charlie's voice cracked. Don's heart clenched. Until now, he could have fooled himself into thinking that this was all a horrible joke. That his brother was actually at CalSci, teaching some unruly freshman class, trying to drum differential equations into heads better suited to quoting Faust and Brittany Spears… "Don, sea pie—"

Don had heard that next sound more than once. LAPD used stun guns rather than conventional weapons whenever possible as a more humane alternative to blowing the suspect away with bullets. The crickle crackle of voltage crossing through air from one electrode to the other was unmistakable.

This was deeper, the sound lower in pitch. Don had heard that, too, although not for several years. That episode was ingrained in his memory: it was a escapee retrieval, a man who'd jumped bail that they'd cornered in a bunk house on a ranch somewhere in the back of Nowhere, New Mexico. The man had very little to arm himself with, but he'd made do with what he could find. What he'd found was a cattle prod. Same principle as a stun gun but with a lot more pain and suffering associated. Stun guns would take someone down and be done with it. Cattle prods pushed large animals around through the judicious application of discomfort. Cattle prods pushedconfessions out of recalcitrant prisoners in third world countries where human rights were considered an expendable luxury.

This cattle prod pushed a scream out of Charlie that Don would hear in his nightmares for the rest of his days. He broke out into a sweat, clenching the phone until Megan was certain that it would shatter in his hand, listening to the gasping sobs of a man trying to catch his breath after being tortured.

"I'm liking this," the woman said across the miles. "I'm teaching two pigs that they don't mess with me, both at the same time. Guess we can talk about efficiency, can't we, Professor Eppes?"

The second scream didn't have the same length or energy behind it.

"Stop it!" Don yelled at the phone. "Stop it! You've made your point! Stop it!"

"Ooh, hit a nerve, did we?" She giggled, pleased with her own play on words.

"Don't hurt him any more," Don begged, trying to catch David's eye. How much longer?

David too had sweat breaking out, trying to coax more speed out of his tracing equipment. Not yet. A few seconds more. Almost there…

"I'd start working on getting my money together, if I were you," she told him. "You're flunking Professor Eppes' class on how to rescue him. Not real fun to flunk out, is it? Professor Eppes knows that. At least, he knows it now."

The next scream was definitely weaker this time. Don fought down a curse.

David shook his head at Don. His own hands were shaking over the dials. Keep her talking. A few seconds more and we'll have her…

He had to keep the woman on the phone. Had to keep the connection alive, so that David could complete the trace. He steeled himself. "Sounds like you know what it feels like, flunking out. That your problem, sister? Flunking out? Just not good enough? A failure?" He drew the word out, trying to make it last. Trying to keep the connection alive. More time. More time. Charlie's life depends on it.

"I am good enough!" she screamed back at him, stung. "I am good enough! I'm better than you! And I'll prove it! I'll prove it!" She hung up on him, but not before Don and the other could hear the remnants of one last cry.

"Dammit!"

"David?" Praying. Hoping against hope.

The agent shook his head. "Got a partial, Don. I've narrowed it down to this sector," he pointed to an area on the wall map, "but I can't be any more specific than that."

"Twenty blocks," Megan realized. "She gave us until four o'clock. Don, we can't search that many blocks, not in time!"

Don closed his eyes, praying for divine inspiration. "You're right; we can't. We have to outthink this bitch. We've already seen that. When we follow her trail, we lose. When we outthink her, when we grab the initiative, we win. We got her gang by predicting where they would be. We have to do it here, too."

"Don," David protested, "Charlie was the one who predicted where they'd hit. It was his equation—"

"We've got twenty blocks to narrow down." Don glared at his team, daring them to come up with a solution. "We're damn good federal agents! We've solved cases without Charlie, by using our own brains! So think, dammit! What do we know about this bitch?"

Megan turned to David. "Play the tape back, David," she requested, radiating a brittle calm. "I need to hear it again." She glanced over at the senior member. "Don, you don't need to stay through this."

"I'm staying." Short. Hard.

It was worse the second time around, worse because he knew what was coming. Knew that the next moment would bring another cry of pain, wondering if he could have phrased things differently so that the bitch wouldn't have hurt Charlie. Wondering if he could have said this or that, just to buy David those extra seconds he needed to pinpoint where the bitch was holding his brother.

Profiling: the application of psychological principles so that a character description could be drawn of a suspect. Had learning all those principles allowed Megan to learn how to divorce herself from her real emotions when she needed to? Don envied the profiler her composure. Megan sat there, arm in a sling, making notes with a pencil on a spare piece of paper. She listened, and listened again, ignoring Don's attempts to draw blood from his own lip.

Don couldn't stand it any longer. "Megan?"

"Female, early twenties," she said. "And Don, I think she might be a former student of Charlie's."

"What?"

"Listen to what she says. No, not what she says, but how she says it. Listen to how she addresses you: Donnie boy. Only once does she address you by your title of Special Agent, and that only when she wants to make the point that she's talking to the FBI. The other times she mocks you with the diminutive form of your first name."

"And—?"

"She never does that for Charlie. Charlie is always 'Professor Eppes', as though she's accustomed to addressing him in that fashion. Accompanied with the reaction you got when you talked about flunking…" Megan nodded slowly to herself. "This may not be about out-smarting the FBI at all, Don. This may be about Charlie, with you as the convenient lever. This could be personal. Let's get a list of the students that Charlie's flunked over the last couple of years."

"'Professors don't fail students; students fail themselves,'" David murmured.

"What was that, David?"

A weak smile. "Something one of my own professors told me, back in school. A course in sociology, that was not going well. 'Professors don't fail students; students fail themselves.' After that talk, I started applying myself."

"How'd you do?"

"B plus." Another weak smile. "He told me it would have been an A if I'd worked that hard all semester long."

Don nodded. "We're all going to be working that hard for the next few hours." He looked at his watch. "All right, people, we've got three hours, and presumably this bitch will call back at that time to tell me where to take the ransom. After the last ransom fiasco, she won't be taking my word for anything. David, be ready. I want you to be able to pinpoint her location as fast as possible, if we can't find her before that."

"On it."

"Megan, requisition the manpower you need with highest priority. Go to CalSci and go through their records. Get a court order if they won't cooperate. Get Larry Fleinhardt to intercede for you. Whatever. Just get me a list of possibles. I'll get Colby to—" He stopped short, thinking.

"Don?"

"Run the tape again."

"Don?"

"Just do it."

David pushed the button on the recorder, listened to the whir of the tape rewinding, the click as it started forward. They had almost memorized the words—

"There. Stop it. Those two seconds."

"Don?"

David rewound the tape so that the three could listen again.

"'Okay. I guess he's earned this,'" emerged from that husky female voice. "'Professor Eppes, your brother wants to hear from you.'"

"'Don?'" A pause for a breath. "'Don, sea pie—'"

"There!" Don said. "'Sea pie.' What did Charlie mean? 'Sea pie'?"

"He was giving us a clue," Megan mused, trying to decipher the meaning. "Sea? Is he by the ocean? Near a pier?"

"Not a chance. Look at the map where the call came from." David pointed. "He's several miles away from the shoreline. How about 'pie'? There are a few bakeries in those blocks. Not ones that get shining recommendations from the Department of Health, but they stay in business."

Don thought. There was something missing, something not right with what his team was saying, something that didn't really fit…

"Numbers," he finally said. "Charlie is obsessed with numbers. They're what he notices."

David's eyes narrowed. "'Sea pie' is not a number."

"Not 'sea'. 'C'. Like a variable. Charlie's always talking about variables, and those are represented by letters."

"Speed of light? Isn't that what 'C' represents?" David cast about, hunting in his memory for the answer.

"That's physics, not just a number. What is the speed of light? A hundred and eighty six thousand miles per some unit of time? How does that help?" Don too was trying to correlate the information.

"How about 'pie'?" Megan pursued. "What does that mean?"

Don reached back into his own high school math classes. He hadn't been bad at the subject but he'd hated numbers on principle; Charlie was so good that he'd outshone Don without even trying. Then those same teachers would look at Don and wonder why he couldn't be even half as good as his little brother…

"Not 'pie'. Not apple pie. 'Pi', that mathematical constant that gets used in figuring out stuff about circles." The memory came hard. "It's a number. It's a number that keeps on going, that has lots of numbers in it…" he trailed off.

"Pi." David nodded with grim triumph. "Three point one four one and oh, damn, I forget the rest. I can figure it out, I think. You divide seven into twenty one; no, twenty two…" he trailed off.

"But what does it mean?" Megan asked. "Why would Charlie be telling us to think about circles? This is tougher than any of those codes that the suspect sent."

"But it has to mean something," David declared. "Charlie wouldn't have said those words otherwise."

"What would Charlie have seen that would have those numbers? Not just those numbers, but those numbers preceded by the letter 'C'?" Don already knew the answer. "A license plate. Partials: California plates Charlie three one four one and who knows how many digits are part of pi. We look in those twenty blocks," and he pointed to David's map, "for a vehicle with those plates. You," and the next finger aimed at Megan with her arm still in its sling, "stay behind. Run the plates, correlate any possibles with students that Charlie's flunked in the last few years. Failed themselves," he corrected himself, looking at David.

Let's not fail Charlie.