Trixie remembered learning that the human body was, like, sixty percent water. How many degrees below zero did it have to get before you literally froze to death?

  �Come on,� Willie said. �Let�s get some grass.�

  The last thing Trixie wanted to do right now was smoke weed. She tried to shake her head, but even that set of muscles had stopped working. When she didn�t get up, he turned away, as if she wasn�t even worth bothering with. �Wait,� she said, and although he didn�t look at her, he stopped moving. She wanted to explain how her feet felt like blocks and her fingers stung so bad that she had to keep biting down on her lower lip. She wanted to tell him how her shoulders hurt from trying not to shiver. She wanted to tell him she was scared and that when she imagined running away, this hadn�t entered into it. �I c-can�t move,� Trixie said.

  Willie knelt beside her. �What can�t you feel?�

  She didn�t know how to answer that. Comfort? Safety?

  He began unlacing Trixie�s boots. Matter-of-factly, he cupped his hands around one of her feet. �I don�t have a sleeping bag. I let my cousin Ernie take it, he�s one of the mushers, and the officials check to see if you have one before you start the race.� Then, just when Trixie could move her toes again, just as a searing burn shot from her nails to the arch of her foot, Willie stood up and left.

  He came back a few minutes later with an armful of dead grass.

  It was still dusted with snow; Willie had dug it out from the edge of the riverbank. He packed the grass in Trixie�s boots and mittens. He told her to stuff some under her parka.

  �How long will it snow?� Trixie asked.

  Willie shrugged.

  �How come you don�t talk?�

  Willie rocked back on his heels, his boots crunching in the snow. �How come you think you have to talk to say something?� He pulled off his mittens and toasted his hands over the fire. �You�ve got frostnip.�

  �What�s that?�

  �Frostbite, before it happens.�

  Trixie tried to remember what she knew about frostbite. Didn�t the affected body part turn black and fall off? �Where?� she panicked.

  �Between your eyes. On your cheek.�

  Her face was going to fall off?

  Willie gestured, almost delicately, in a way that let her know he wanted to move closer to her, to place his hand on her. It was at that moment that Trixie realized she was in the company of a boy who was stronger than she was, in the middle of nowhere, a good twenty-five miles away from anyone who�d hear her scream. She leaned away from him, shaking her head, as her throat closed like a rose after dark.

  His fingers caught her at the wrist, and Trixie�s heart started hammering harder. She closed her eyes, expecting the worst, thinking that maybe if you�d lived a nightmare once it wasn�t quite as bad the second time around.

  Willie�s palm, hot as a stone in the sun, pressed against her cheek. She felt his other hand touch her forehead, then sweep down the side of her face to cup her jaw.

  She could feel calluses on his skin, and she wondered where they�d come from. Trixie opened her eyes and, for the first time since she�d met him, found Willie Moses looking right at her.

  Skipper Johanssen, the mitochondrial DNA expert, was a woman. Bartholemew watched her pour sugar into her coffee and look over the notes on the case that he�d brought. �Unusual name,� he said.

  �Mom had a Barbie thing going on.�

  She was beautiful: straight platinum hair that swept the middle of her back, green eyes hidden behind her thick-framed black glasses. When she read, sometimes her mouth formed the words. �What do you know about mitochondrial DNA?� she asked.

  �That you can hopefully use it to compare two hairs?�

  �Well, yeah, you can. The real question is what you want to do with that comparison.� Skipper leaned back in her chair. �Thanks to C.S.I., everyone�s heard about DNA analysis. Most of the time they�re talking about nuclear DNA, the kind that comes, in equal halves, from your mother and your father. But there�s another kind of DNA that�s the up-and-comer in the forensic community-mitochondrial DNA. And even though you may not know a lot about it, you-and the rest of the world-know the largest case in history where it was used: 9/11.�

  �To identify the remains?�

  �Exactly,� Skipper said. �Traditional efforts didn�t work-they couldn�t find intact teeth, or bones that weren�t crushed, or even anything to X-ray. But mtDNA can be used to profile samples that have been burned, pulverized, you name it. All scientists need is a saliva sample from a family member of the deceased in order to make a comparison.�

  She picked up the hair sample that Max had scrutinized under a microscope the previous day. �The reason we can test this for DNA-without a root attached-is that a cell isn�t made up of just a nucleus. There are many more parts-including the mitochondria, which are basically the powerhouses that keep the cell functional. There are hundreds of mitochondria in a cell, as compared to a single nucleus. And each mitochondrion contains several copies of the mtDNA we�re interested in.�

  �If there�s so much more mtDNA than nuclear DNA, why isn�t it used all the time for criminal profiling?� Bartholemew asked.

  �Well, there�s a catch. Typically, when you get a nuclear DNA profile, the chances of finding another person with that profile are one in six billion. Mitochondrial DNA stats are far less discriminating, because unlike nuclear DNA, you inherit mtDNA only from your mom. That means that you and your brothers and sisters all have the same mtDNA she does�and that her mom and siblings do, and so on. It�s actually fascinating-a female egg cell possesses tons of mitochondria, as compared to the sperm cell. At fertilization, not only are the few sperm mitochondria totally outnumbered, they�re actually destroyed.� Skipper smiled brightly. �Natural selection at its finest.�

  �It�s a pity you have to keep us around for that whole fertilization thing in the first place,� Bartholemew said dryly.

  �Ah, but you should see what�s going on next door to me in the cloning lab,� Skipper replied. �Anyway, my point is that mtDNA isn�t helpful if you�re choosing between two biological siblings to pinpoint a suspect, but it�s a nice tool if you�re looking to exclude someone nonrelated from an investigation. Statistically, if you test fifteen spots on the DNA strand, there are more than an octillion nuclear DNA profiles, which is awfully nice when you�re in front of a jury and trying to pin down a particular individual. But with mtDNA, there are only forty-eight hundred sequences logged to date�and another six thousand reported in scientific literature. With mtDNA, you might wind up with a relative frequency of point one four or something like that-basically, a subject will share a profile with four percent of the world�s population. It�s not specific enough to nail a perp without reasonable doubt in front of a jury, but it would allow you to rule someone out as a suspect because he or she doesn�t have that particular profile.�

  �So if the mtDNA profile of the hair found on the victim�s body doesn�t match the one for Trixie Stone�s hair,� Bartholemew said, �then I can�t link her to the murder.�

  �Correct.�

  �And if it does match?�

  Skipper glanced up. �Then you�ve got reasonable cause to arrest her.�

  The sun skipped the Alaskan tundra. At least, that�s how it seemed to Laura, or why else would it be pitch-dark at nine in the morning? She anxiously waited for the flight attendant to open the hatch of the plane, now that they had landed in Bethel. It was bad enough that she had a fear of heights and hated flying, but this was only half a plane, really-the front end was devoted to cargo.

  �How are you doing?� Daniel asked.

  �Fantastic,� Laura said, trying to lighten her voice. �It could have been a Cessna, right?�

  Daniel turned just as they were about to exit the plane and pulled up the hood of her jacket. He tugged on the strings and tied them under her chin, just like he used to do when Trixie was tiny and headed out to play in the snow. �It�s colder than you think,� he said, and he stepped onto the rollaway staircase that led to the runway.

  It was an understatement. The wind was a knife that cut her to ribbons; the act of breathing felt like swallowing glass. Laura followed Daniel across the runway, hurrying into a small, squat building.

  The airport consisted of chairs arranged in narrow rows and a single ticket counter. It wasn�t manned, because the lone employee had moved to the metal detector, to screen passengers on the outbound flight. Laura watched two native girls hugging an older woman, all three of them crying as they inched toward the gate.

  There were signs in both English and Yup�ik. �Does that mean bathroom?� Laura asked, pointing to a doorway with the word ANARVIK overhead.

  �Well, there�s no Yup�ik word for bathroom,� Daniel said, smiling a little. �That actually translates to �the place to shit.� �

  The single door split off to the right and the left. The men�s and women�s rooms were not marked, but she could glimpse a urinal in one direction, so she walked the opposite way. The sinks were operated by push pedals; she pumped one to start the flow of water and then splashed some on her face. She looked at herself in the mirror.

  If someone else walks into the bathroom, she thought, I will stop being a coward.

  If the family outside has made it through security, to the gate.

  If Daniel is facing forward, when I come out.

  She used to play this game with herself all the time. If the light changed before she counted to ten, then she would go Seth�s after class. If Daniel picked up before the third ring, she would stay an extra five minutes.

  She�d take these random occurrences and elevate them to oracles; she�d pretend that they were enough to justify her actions.

  Or lack therof.

  Wiping her hands on her jacket, she stepped outside to find the family still crying near the metal detector and Daniel facing out the window.

  Laura sighed with relief and walked toward him.

  Trixie was shivering so hard that she kept shaking off the quilt of dead grass Willie had used to cover them for warmth. It wasn�t like a blanket you could just pull over yourself; you had to burrow down and think warm thoughts and hope for the best. Her feet still ached and her hair was frozen against her head. She was consciously awake-somehow she thought that sleeping was too close to the line of being blue and stiff and dead, and that you might pass from one side to the other without any fanfare.

  Willie�s breath came out in little white clouds that floated in the air like Chinese lanterns on a string. His eyes were closed, which meant Trixie could stare at him as much as she wanted. She wondered what it was like to grow up here, to have a snowstorm hit like this and to know how to save yourself, instead of needing someone to do it for you. She wondered if her father knew this sort of stuff too, if elemental knowledge about living and dying might be underneath all the other, ordinary things he knew, like how to draw a devil and change a fuse and not burn pancakes.

  �Are you awake?� she murmured.

  Willie didn�t open his eyes, but he nodded the tiniest bit, and a stream of white flowed out of his nostrils.

  There was a warm zone connecting them. They were lying two feet apart, with grass heaped in the space between their bodies, but every time Trixie turned his way she could feel heat conducting through the dried straw, pulsing like light from a star. When she thought he might not notice, she inched infinitesimally closer.

  �Do you know anyone who ever died out here?� Trixie asked.

  �Yeah,� Willie said. �That�s why you don�t make a cave in a snowbank. If you die, no one can ever find you, and then your spirit won�t ever rest.�

  Trixie felt her eyes get damp, and that was awful, because almost immediately her lashes sealed shut again. She thought of the ladders she�d cut on her arms, the way she�d wanted to feel real pain instead of the hurt gnawed on her heart. Well, she�d gotten what she wanted, hadn�t she? Her toes burned like fire; her fingers had swollen like sausages and ached. The thought of that delicate razor blade being drawn across her skin seemed, by comparison, ridiculous, a drama for someone who didn�t really know what tragedy was.

  Maybe it took realizing that you could die to keep you from wanting to do it.

  Trixie wiped her nose and pressed her fingertips against her eyelashes to dissolve the ice. �I don�t want to freeze to death,� she whispered.

  Willie swallowed. �Well�there is one way to get warmer.�

  �How?�

  �Take off our clothes.�

  �Yeah, right,� Trixie scoffed.

  �I�m not bullshitting you.� Willie glanced away. �We both get�you know�and then huddle together.�

  Trixie stared at him. She didn�t want to be pressed up against him; she kept thinking of what had happened the last time she was this close to a boy.

  �It�s just what you do,� Willie said. �It�s not like it means anything. My dad�s stripped down naked with other guys, when they get stuck overnight.�

  Trixie pictured her father doing this-but stopped abruptly when she got to the part where she had to imagine him without clothes.

  �Last time it happened, my dad had to cuddle up to old Ellis Puuqatak the whole night. He swore he�d never leave home again without a sleeping bag.�

  Trixie watched Willie�s words crystallize in the cold, each as differentiated as a snowflake, and she knew he was telling her the truth. �You have to close your eyes first,� she said, hesitant.

  She shucked off her jeans, anorak, and sweater. She left on her bra and panties, because she had to.

  �Now you,� Trixie said, and she looked away as he pulled off his coat and his shirt. She peeked, though. His back was the color of the outside of an almond, and his shoulder blades flexed like pistons. He took off his jeans, hopping around and making little sounds, like a person at the town pool who makes a big deal when he finally manages to get into the cold water.

  Willie spread some grass on the ground, then lay down and motioned for Trixie to do the same. He drew their jackets over them, like a blanket, and then covered these with more grass.

  Trixie squeezed her eyes shut. She could feel the rustle of the straw as he moved closer and the itch of the grass on her bare skin as it caught between them. Willie�s hand touched her back, and she stiffened as he came up behind her, curling his knees into the hollow bowl made by the bend of her own. She took deep breaths. She tried not to remember the last boy she�d touched, the last boy who�d touched her.

  The inferno began where his fingers rested on her shoulder and spread to every spot where their skin was touching. Pressed up against Willie, Trixie didn�t find herself thinking about Jason, or the night of the rape. She didn�t feel threatened or even frightened. She simply felt, for the first time in hours, warm. �Did you ever know someone who died?� she asked. �Someone our age?�

  It took Willie a moment, but he answered. �Yes.�

  The bitter wind beat against their tarp and made its loose tongue rattle like a gossip�s. Trixie unclenched her fists. �Me too,� she said.

  Bethel was technically a city, but not by any normal standards. The population was less than six thousand, although it was the closest hub for fifty-three native villages along the river. There were only about thirteen miles of roads, most of them unpaved. Daniel opened the terminal�s door and turned to Laura. �We can get a taxi,� he said.

  �There are taxis here?�

  �Most people don�t have cars. If you�ve got a boat and a snow-go, you�re pretty much set.�

  The cab driver was a tiny Asian woman with a massive bun perched on her head like an avalanche waiting to happen. She wore fake Gucci sunglasses, although it was still dark outside, and was listening to Patsy Cline on the radio. �Where you go?�

  Daniel hesitated. �Just drive,� he said. �I�ll tell you when to stop.�

  The sun had finally broken over the horizon like the yolk of an egg. Daniel stared out the window at the landscape: pancake flat, windswept, opaque with ice. The rutted roads had houses pitted along them, ranging from tiny shacks to modest 1970s split-levels. On the side of one road sat a couch with the cushions missing and its overstuffed arms dusted with frost.

  They drove past the neighborhoods of Lousetown and Alligator Acres, the Alaska Commercial Company store, the medical center where Yup�ik Eskimos received free treatment. They passed White Alice, a huge curved structure that resembled a drive-in movie screen but that actually was a radar system built during the Cold War. Daniel had broken into it a hundred times as a kid-climbed up through the pitch-black center to sit on top and get drunk on Windsor Whiskey.

  �Okay,� he told the cab driver. �You can stop here.�

  The Long House Inn was covered with ravens. There were at least a dozen on the roof, and another group battled around the remains of a torn Hefty bag in the Dumpster off to the side. Daniel paid the driver and stared at the renovated building. When he�d left, it was on the verge of being condemned.

  There were three snow machines parked out front, something Daniel filed away in the recesses of his mind. He�d need one, after he figured out what direction to head to find Trixie. He could hotwire one of these, if he still remembered how, or take the honorable route and charge one to his MasterCard. They were sold in the Alaska Commercial store, at the end of the dairy aisle, past the $6.99 gallons of milk.

  �Did you know a group of ravens is called an unkindness?� Laura said, coming to stand beside him.

  He looked at her. For some reason, the space between them seemed smaller in Alaska. Or maybe you just had to get far enough away from the scene of a crime to start to forget the details. �Did you know,� he replied, �that ravens like Thai food better than anything else?�

  Laura�s eyes lit up. �You win.�

  A banner had been strung across the doorway: K 300 HEADQUARTERS. Daniel walked inside, stamping his boots to get the snow off. He�d been a kid when this dogsled race was just getting organized, when locals like Rick Swenson and Jerry Austin and Myron Angst-man had won the pot of a few thousand dollars. Now the winnings were $20,000, and the mushers who came were stars with corporate backing for their dog kennels-Jeff King and Martin Buser and DeeDee Jonrowe.

  The room was crowded. A knot of native kids sat on the floor, drinking cans of Coke and passing around a comic book. Two women answered phones, another was carefully printing the latest splits on a white board. There were Yup�ik mothers carrying moon-faced babies, elderly men reading the scrapbooks of newspaper clippings, schoolgirls with blue-black braids giggling behind their hands as they helped themselves to the potluck stews and cobblers. Everyone moved pendulously in layers of winter clothing, astronauts navigating the surface of a distant planet.

  Which, Daniel thought, this might as well be.

  He walked up to the desk where the women were answering phones. �Excuse me,� he said. �I�m trying to find a teenage girl�� One woman held up a finger: Just a moment.