I'm not sure where Rachel's story starts.

During her trial? On her first day in prison? In the months after she lost her mother, or in the split second when she pulled the trigger?

Maybe you saw her on the news: Rachel Boone, teenaged murderer.

Maybe you watched the grainy video of a blurry figure raising a trembling gun. Flame spits from the barrel, the body crumples, and Rachel falls to her knees.

She goes by her mother's maiden name now. Rachel Kravitz.

I'll start with her in the compound in the Ventura foothills, standing at a workbench in the shop building, carving a grave marker. Holding a chisel low in her left hand, tapping with a mallet. Her sweat-damp hair sticking to her face in the Californya heat, wearing a tank top and jeans.

She had dark hair and dark eyes. A pretty face, I guess, but Rachel's more than pretty. She had a strong face, even at seventeen. Striking the chisel with steady blows, wood curling from the cutting edge, her wiry strength clear in her arms.

She dressed plain, except for the sparkly fingernail polish, which she wore to amuse her little sister Audrey. Trying to bring some happiness in Audrey's life, some softness.

Not that you could've called Rachel soft. Or happy. At least not back then.

Now she knows me, so her life is all rainbows and ponies. That's just the kind of guy I am.

Anyway, she set the mallet aside and started using a v-tool to sharpen the K in Naomi Kravitz. She tilted the handle, working with the wood grain, her brow furrowed in concentration.

Then the shop door banged opened and a gust of warm afternoon air brought the scent of sand and sage.

Rachel smiled when she saw her sister silhouetted in the doorway, but didn't say anything. Words didn't always come easily to her.

"What're you working on?" Audrey asked.

"Nothing," Rachel said, drawing a cloth over the grave marker.

Audrey wrinkled her nose in disbelief. "Dad wants you. There's a board meeting."

"I'll give that a miss."

"He told me to get you," Audrey said.

"I've been sitting in on his meetings since I was ten." Rachel rubbed the ache from her forearm. "If I haven't learned his lessons by now, I never will."

"At least he wants you there," Audrey said, leaning against the table saw.

"Yeah, because he thinks I'm his clone."

Their father had started grooming Rachel to work in his company when she'd turned eight. He'd taught her to sit still and think things through. He'd taught her to listen to what people said and hear what they meant. At twelve, she'd visited the branch offices in Virginya and the Everglades. At thirteen, he'd taught her to drive and shoot--because he'd learned to drive and shoot at thirteen, and he wanted to make her exactly like him.

When she was seven and afraid of the dark, he'd told her that monsters weren't the only dangerous things lurking in shadows. You're there, too, he'd said. If you can't see them, they can't see you.

"He thinks you're useful," Audrey said, chewing on her lower lip. "Not like me."

Rachel touched the canvas covering the grave marker. "You remind him of mom."

Audrey reminded Rachel of their mom, too, with her sweet face and calm gentleness. Rachel thought of Audrey as an oasis in the desert. Nothing flashy, just a lifegiving spring of sweet water. She was the best thing in Rachel's world.

"I know what you're making," Audrey said. "So does Dad."

Rachel fell back on her old standby: silence.

"Can I see it?" Audrey asked.

Rachel rubbed her face with a sweaty palm. No. No, you can't see it. You can't be reminded of death and loss and grief and rage. I need you to grow straight and strong and bright, not dense and clenched like me. But she couldn't refuse the hope in Audrey's eyes. After a long moment, she removed the canvas to reveal at the wooden slab. Rough and unfinished, the edges not even beveled yet. So pathetically inadequate.

Audrey traced her finger under the name, Naomi Kravitz, along the outlined letters that read Beloved Mother. "Why did you use 'Kravitz' instead of 'Boone'?" she asked.

"Becaause she's dead now," Rachel said, her voice hard. "Boone can't have her anymore."

Audrey frowned. She didn't like the tension between Rachel and their father--she didn't like when Rachel called him 'Boone' instead of 'Dad.' "Um, why are you using wood instead stone?"

"It's plum wood," Rachel told her.

Their mom used to call Audrey 'Miss Plum.' She'd only called Rachel 'Rachel,' but that was okay, Rachel understood. She wasn't the sort of girl who got nicknames.

Audrey ducked her head and started to cry.

Rachel hesitated, feeling helpless and clumsy. She didn't think of herself as being good with emotions. Not her own, not anyone else's. But after a pause, she held her sister. "I'm sorry," she murmured into Audrey's hair, even though she didn't know what she was apologizing for.

"I just …" Audrey sniffled. "I miss her."

"Yeah."

Audrey wiped her nose on Rachel's shoulder. "That's the sweetest thing ever. Plum wood."

Rachel stood there, not knowing what to say, until one of the guards appeared in the doorway: a big man with a shaved head, wearing desert camo and mirrored shades. A filtration unit dangled from a strap around his neck and his assault rifle pointed at the floor.

"Miss Boone," he told Rachel. "Your father's waiting in Conference Room B."

She looked at him. "My sister told me."

"He tasked me with getting you."

Rachel kept looking at him. Her eyes concealed her feeling as well as his mirrored sunglasses.

The guard raised his hands. "C'mon, Rachel. I'm not going to say no to your father. Maybe you can get away with that, but me? He'd eat me alive."

"It's just a meeting," Audrey said, with a pleading note in her voice.

Rachel said okay and followed the guard outside. She felt the sun on her face, sloping hot and golden over the hardscrabble mountains. Classical music drifted from one of the lower cabins, which meant Mr. Subramanian was baking bread again. Farther along, a circle of wilted wildflowers surrounded the trunk of a live oak scarred by a series of slashes like clawmarks.

Not mountain lion. Too big for mountain lion.

Rachel followed the guard past the cottage where the Drigger family lived, in three rooms with flat-screens instead of windows. Cut off from the world, except for the data flow her father arranged. A side door opened in the wall and two researchers headed toward the main lab, a brick building with steep roofs, a holdover from the agricultural college that had stood that spot in the 1880s.

The government had bought the property after World War II, and for sixty or seventy years various military departments shuffled it back and forth until Rachel's father, Carson Boone, took it private. He'd initially worked for a defense contractor that specialized in information technology. But after the Seventeen Seconds, he'd started a private firm, ARIES: Applied Research International Engineering Solutions. He'd purchased the property, five hundred acres of canyon and scrub in the Los Padres Mountains.

Remote, secure, and fitted with his experimental protocols. And test subjects, like the Drigger family.

Rachel stopped outside a three-bedroom house that could've been plucked from a suburb somewhere. Her home. Inside, she showered and dressed in clean pants and one of her better T shirts. She put on her mother's carnelian earrings, and daydreamed about getting her nose pierced. Mostly because she didn't want to think about the board meeting.

She went to the office building, four stories of cement and glass that her father once said looked like a second-rate Frank Lloyd Wright. Her mother had laughed and said that even a second-rate Frank Lloyd Wright was beautiful.

Rachel paused, remembering her mother's laughter. Then she made herself forget and pushed inside, past the guards to the stairs.

Three people sat around the table in Conference Room B, and four more appeared on video. Her father apologized for Rachel's tardiness and she sat beside him, taking notes, keeping her expression neutral, thinking about her mother again.

About what her father had done to her.

After the meeting, she followed Boone toward his office, because he told her to. Carson Boone didn't look like anything special. Average height and average weight. Clean-shaven, short hair. In good shape. At first glance, he seemed perfectly average.

If you looked closer, though, he sort of blurred at the edges. Like he was trying to look average, like that was a mask he wore. His eyes were mild and his voice soft. He never lost his temper, but there was something almost inhuman in his stillness, something reptilian.

Rachel once told me that her father wasn't a sociopath. What he was, she'd said, was a fanatic. He saw himself as a hero, a savior: the last barricade between the ignorant masses and what he called the 'Terminus', the terminal event. A sociopath, she'd told me, wouldn't be nearly as dangerous.

At the end of the hallway, Rachel and her father passed a window that opened into a reception area--and paused when they saw Audrey curled on a padded bench, her feet tucked under like a cat, drawing in her sketchpad. She looked comfortable.

Audrey's ability to find a comfortable spot always made Rachel smile. She couldn’t curl up like a cat if you spotted her a bowl of warm milk and a ball of yarn.

Audrey didn't see them; she just kept drawing and chewing at a strand of hair.

In a quiet voice, Boone said, "You're still angry with me."

Rachel didn't answer. He'd taught her that: if you don't have anything to say, keep quiet.

"About your mother," he told her, breaking his own rule.

She smiled faintly as Audrey shifted into an even-more-comfortable position on the bench.

"I explained that," her father said. "You should understand."

"Do you need something?" she asked him.

"Yes, Rachel. I need you to understand."

A surge of anger rose into her face, and she bowed her head so he wouldn’t see her cheeks flush. "I understand perfectly."

"Yet you're still angry," he said, grabbing her arm.

She listened to the blood pounding in her ears.

"When you're this angry, Rachel," he said, infuriatingly calm, "you need to use your feelings. You need to harness your anger. You need to make a decision, to make a plan. "

"I'm going to wait," she told him.

"And then?"

She lifted her head. "I'm going to protect my sister."

"Protecting her is my job," her father said.

Rachel jerked her arm from his grip. "Like you protected Mom?"

"I'm protecting us all." He measured her with his shark eyes. "You know the stakes."

"All I know is this," she said. "If you ever touch Audrey, I'll kill you."