She'd left him out in the lab, saying she'd be back in a minute. Her father-she desperately wanted to think of him as only Nathan, but after all these years it was hard-probably would be upset that she'd left him alone.

But why did he leave him here with me in the first place? Especially after last night.

Sophia opened the door but stopped short when she saw Jonathan standing in her office by her desk. She eyed her unmade cot against the wall and her pile of clothes on the floor. He turned and smiled disarmingly when she entered.

"Sorry. Didn't mean to startle you. Would it be all right if I . . ." He motioned toward the bathroom.

"Of course. Go ahead," Sophia said. The second he closed the door, she scooped up her laundry and tossed it under the cot. She pulled the blanket up and saw there was a salsa stain on it from the burrito she'd had last night. She put her pillow on top of the stain and shook her head. Of all nights to be a slob.

The door opened and she stood up so fast her glasses fell off. She bent to get them, but Jonathan beat her to them. He smiled and handed them to her.

"Should we go back out?" Jonathan asked.

"Yes. Sure," Sophia said. Jonathan motioned for her to go first. She thanked him and left her office with Jonathan close behind.

"How do you know my father, Mr. Hall?" Sophia asked when they were back in the lab. He seemed more interested in her animal cages than in her. He answered without turning around.

"I don't. And call me Jonathan."

"You-"

"So what is all this about?" Jonathan asked, waving at the cages and the maze table.

"It's for my research."

"This whole lab is just for you?"

"I used to have a staff. In fact, most of the initial work was done at Kring Laboratories, a research facility in Nigeria, but things . . . changed."

"I'm assuming the change has something to do with the guard outside your door. He's not keeping people out, is he." It wasn't a question.

Who is this guy?

"If you don't know my father, then how-"

"You show me yours and I'll show you mine."

"Excuse me?" Sophia said, feeling her face redden.

"Give me the Cliff Notes version of your research and I'll tell you anything you want to know. Deal?" he asked, putting out his hand.

Sophia shook it and agreed, noticing how soft his hand was. She doubted revealing the research to a stranger was what her father had in mind when he asked her to stay with Jonathan. Which was exactly why she agreed so quickly.

"Do you know what a prion is?" she asked, wiping off a whiteboard and grabbing a marker.

"Something to do with the brain, isn't it?"

"Yes, that's right. Basically," she said, drawing something that resembled a string on the board, "there are harmless proteins in all of us-you, me, animals, plants-everything. For these proteins to assume a functional shape-be able to do anything-they have to fold, sort of like this."

Sophia drew a kind of coiled ribbon beside the string, trying her best to simplify the process for Jonathan. He nodded, so she assumed she was doing all right.

"For some reason-nobody really knows why-sometimes one of these benign proteins will fold abnormally," she said, continuing to draw. "But the really interesting part-and the real danger-is not that a protein can fold, but what an abnormally folded protein does after it folds. They're capable of coopting any other proteins they come in contact with, making it a copy of itself."

"Like a zombie," Jonathan said as Sophia finished drawing something that looked like an untied shoelace.

"Exactly, but a microscopic zombie that will never get a movie deal. It travels through the body, changing perfectly healthy proteins into copies of itself. When these misfolded prions get into the nervous system and the brain, you get prion diseases like Creutzfeldt-Jakob disease, fatal insomnia, and even some types of Alzheimer's."

"You can die from insomnia?"

"Um, yes, but it's not the kind of insomnia you're probably thinking of. Only twenty-eight families in the world have been identified with the gene responsible for-but I'm getting off topic," she said, batting the air like she was erasing what she just said.

"Sorry. Prions. You were saying," Jonathan said.

"Yes, someone with a prion disease experiences impaired brain function causing memory changes, personality changes, dementia, and problems with movement. All of these get worse over time," she said, putting down the marker and walking over to where the cages lined the wall.

"Is that what your father has?" Jonathan asked.

"Yes, he has kuru, a type of prion disease that used to be quite prevalent in New Guinea back in the 1970s."

"The seventies? How long has he known he had it?" Jonathan asked.

"He was diagnosed shortly after returning from New Guinea around 1973. Even though they could detect it in his blood, kuru has a long incubation period before symptoms start to show up. Decades," she said. She left out the part about that being the same year she was born-partly because with her recent revelations, she wasn't all that sure about the veracity of what she'd always assumed were facts about her early childhood. And partly because she wasn't that crazy about admitting to Jonathan that she was over forty.

"Wait a minute. Kuru. Kuru. Why do I know that name?" Jonathan asked, but he didn't appear to be asking her. Then it seemed to come to him. "Kuru. I think I played a video game that had kuru in the backstory a year or two ago. In fact, I think it was set near Papua New Guinea. But they must have embellished. It was a zombie game. The characters only turned when they-"

Jonathan stopped mid-sentence. Sophia was pretty sure it was because of the look on her face. Even with her connection to Nathan being fictional, she was mortified at the idea of the truth coming out. But she knew the best thing she could do was face it head-on.

"Kuru was at epidemic levels in the 1970s because of the indigenous tribes' practice of ritualistic cannibalism. I'm not familiar with the video game, and I'm sure they did hyperbolize for effect, but it was based on fact. Kuru is very real. And so is the fact that to contract it, Nathan had to have consumed human tissue, including brain."

Jonathan was apparently trying to control his reaction, but when his eyes slightly widened she knew she had to keep going or the emotional turmoil of the last few days would push her over the edge.

"Once symptoms start to show, they typically increase with intensity over several months until they finally result in death. When his symptoms first showed he was told he had six to eighteen months to live," Sophia said. She turned away from Jonathan, took a moment to steady herself, and then opened one of the cages.

"When was that?" Jonathan asked with an even tone. Sophia couldn't be sure, of course, but she liked the idea that he was ignoring the elephant in the room for her sake.

She turned around holding out two tiny white mice, their pink noses furiously sniffing the air. "Five years ago."

"Five years?"

Sophia put the mice down on a table rimmed with six-inch Plexiglas. Jonathan came over beside her and they looked down at her creatures. One was inquisitive and almost hyperactive, zipping here and there in the enclosure. The other lay on its side, pawing at the air and rolling its head back in semicircles, its mouth opening and closing.

"My father had an advantage over others afflicted with a prion disease. He knew it was coming long before the symptoms showed up. It gave him time to prepare."

"Prepare?"

"Yes. His subvocally controlled chair, for instance. He had it developed especially for him."

"Vocal? I can't even see his lips move," Jonathan said.

"Not vocal, subvocal. Like when you read to yourself. The brain still sends electrical impulses to the vocal cords even if you don't speak out loud. The neckband picks those up and translates them into commands-speech, movement-like that."

"Amazing."

"And his voice synthesizer. Most people have to make do with a canned, tinny electronic voice. Even with advancements in the field, the vocal generator always sounds artificial."

"You mean like Stephen Hawking," Jonathan said.

"Sort of. They've actually offered Mr. Hawking much more advanced and natural-sounding voice synthesizers, but he keeps his antiquated one since so many people identify its tone and sound with him. But my father was never one for nostalgia. He spent almost two years recording his own voice so that if and when it happened, his artificial voice would sound like his own. But he also had other advantages."

"You mean money."

"Yes. He had resources others didn't. For the most part, there's next to no research into prion diseases," Sophia said, picking up the hyperactive mouse as it scaled one of the Plexiglas walls in an attempt to escape. She gently put it back down next to its immobile brother.

"Why not?"

"Economics. The law of averages, really. Prion diseases are very rare. Only about three hundred cases are diagnosed in the United States every year. With so many other diseases affecting so many more people in the world, it's hard to justify funding for research."

"Unless you're a gazillionaire who has it," Jonathan said.

She chuckled and agreed.

"So why are we looking at mice?" he asked. Sophia thought he seemed more agitated than before, like he was in a hurry.

God, I'm boring him.

"This is Charlie and Lucy," Sophia said, pointing out that Lucy was the hyperactive mouse. "Can you tell me which one has the prion disease?"

"Charlie looks like he does, but I'm guessing it's a trick question. I'll say Lucy."

"Both answers are wrong."

"Huh?"

"They both have a form of kuru. They've had it exactly the same amount of time and at the same density."

"You cured Lucy?"

"Not yet," she said, walking over to a refrigerator. She took out a bottle filled with blue liquid and returned.

"She looks pretty cured to me," Jonathan said.

"Watch." She filled a hypodermic needle with some of the blue fluid and then injected Charlie with it. For a moment, nothing happened. Then Charlie's convulsions became much more violent. He looked like he was going to tear himself apart.

"Hey," Jonathan said.

"Wait for it," she said.

Then, as abruptly as they'd started, the convulsions stopped. But more than that, Charlie seemed to be under control now. He got up off his side and scampered over to sniff what Lucy was doing. They were identical now, in every way. It was impossible to tell them apart.

"That's not a cure?" Jonathan asked.

"Not yet. The serum, in its simplest form, is healthy proteins from Fred's brain."

"Fred?"

"One of their companions I euthanized earlier. Unfortunately, it's impossible to harvest the proteins needed from a live donor. They're not cured, but they have lived longer than any of the other subjects with the disease."

"And any brain has the proteins they need?"

"No, unfortunately. At first, our tests were all over the map. Sometimes it worked and sometimes it didn't. It was frustrating. Then I found the commonality in the successful cases: I had trained all the positive result donors how to run the maze. The ineffective ones had no training at all. Learning or intelligence has an effect on the brain's proteins. But the donors who did the best on the maze-the smartest donors-produced the best results."

"This formula of yours, that's how your father has survived so long?" Jonathan said.

"Yes," Sophia said. "But I just tweaked it for his specific needs. The original serum, including years of trials, was done in Nigeria."

"I think there's something wrong with your formula," Jonathan said. Sophia looked at the mice and saw one of them convulse and fall over onto its side. "Charlie's down again."

"That's not Charlie, it's Lucy," Sophia said. "Though in a few hours, the same thing will happen to Charlie. It's one of the problems I haven't worked out yet. The final problem, really. The effect is fleeting."

"Still, if you can transfer this to humans it would be worth millions. Billions. Incapacitated patients given their faculties again, even for a few hours, is groundbreaking. Have you published your findings anywhere?"

Sophia felt the familiar pang in her stomach when she thought about the groundbreaking research trapped, like her, on the island. She picked up the mice and returned them to their cages.

"You haven't gone public with this, have you? Any of it," Jonathan said. "He's got you doing all of this just for him."

Sophia just looked at him and didn't say anything. Even without speech, Jonathan seemed to get the message.

"Wait a minute. Christ, he can get out of that chair and walk around? Even for a little while?"

After looking at Jonathan for a few more silent moments, Sophia finally said: "Yes."

"But if the same donor restriction applies to humans . . ." Jonathan trailed off. She figured he either reasoned it out for himself or didn't want to know the answer. She wished she didn't.

For years, pristine donor samples had arrived in a prepared state, neatly packaged and labeled "Kring Laboratories: Human Samples." But a few months ago, like so much of Kring Industries, the research facility was sold off. When the inventory of samples was exhausted, new samples started to come in. Sloppily prepared and sometimes damaged samples. No packaging. No labeling. For fear of hearing what she thought she would, Sophia had kept her questions to herself and buried herself in her work. Something that now tore at her soul.

Unable to keep facing him, Sophia turned away from Jonathan and closed the animal cages. She looked at the creatures behind the bars through blurring vision, realizing for the first time how similar to her they really were. But before her melancholy could reach a crescendo, she felt Jonathan's arms slip around her from behind. Her breath caught and she reflexively leaned back into him, feeling his warm body against her back.

Then she felt the cold steel against her throat.

"What-"

"I'm sorry, but I don't have any choice," he said. "You seem like a good kid and it's pretty obvious you're not aligned with your psychotic father, but he is your father. I'm betting if he sees a knife to your throat he'll let me and my daughter out of here, no matter what he had planned for me."

"I . . . I don't understand," Sophia said. "Your daughter? Who's your daughter?" She resisted the urge to fight, not wanting the blade to dig into her neck.

"You really don't know, do you?"

"Know what?"