Joyce was working at one of the nearby lab tables. She looked up as the door swung shut behind us, and stopped, a perplexed expression crossing her face. She looked from Dad to me, and back to Dad again. Finally, she put down the scalpel she was holding, carefully peeled off her plastic gloves, and started toward us. She was moving slowly, like she was afraid one or both of us might spook.

“Sal?” she said, when she was close enough that she wouldn’t need to raise her voice. The rest of the lab technicians politely ignored us. “What are you doing here?”

“Your sister is here to demonstrate the SymboGen test for the sleepwalking sickness. Isn’t that right, Sally?”

Dad’s hand clamped onto my shoulder. It felt heavier than it should have. I swallowed hard and said, “That’s right. When I was… when Chave got sick, they tested to see if I had the sleepwalking sickness. I can demonstrate.” I snuck a glance up at my father. He was frowning straight ahead, almost like he was no longer paying attention to Joyce, or to me.

“Oh.” Joyce followed my gaze, and bit her lip. Then she focused back on me, forcing a smile through her obvious dismay. “Well, you’re here now, and that means we can maybe make some progress. What do we need?”

I don’t know, I wanted to cry. I’m not supposed to be the one who knows. That was my father, the Colonel, or my sister, the scientist, or my boyfriend, the doctor. I was the one who wandered through life and was gently corrected when I started to drift off course. I was the one who didn’t remember enough to know when she was wrong. So why were people suddenly looking to me like I was going to have answers? Answers weren’t my job.

But there was no one to provide them for me. I sniffled as softly as I could, hoping no one would notice, and said, “Dad said you had some sick people here. I need to see one of them. And I’m going to need a portable UV wand.”

“And…?” prompted Joyce.

I shook my head. “That’s all. A sick person, and a portable UV wand.”

My father’s hand tightened on my shoulder. “If that’s all you needed, why did you make me bring you here?”

“Ow.” I stepped away from his hand, turning to glare at him. “I told you why back at the house. I need to understand what’s going on. I need to ask questions and get answers, not get more dismissals and half-truths. I need—”

I stopped midsentence. My father’s face was turned toward me, but he wasn’t really looking at me anymore; his eyes were unfocused, and one corner of his mouth was starting to sag downward, like he was in the early stages of a stroke. The sound of drums grew even louder in my ears as I realized just how erratic his behavior had become over the course of the day. He’d gone from normal to overly solicitous to aggressive, all without the normal stimulus I would expect to trigger such shifts in mood.

Unless something I couldn’t see was triggering them. I took a step backward, moving away from him.

“Sal?” Joyce sounded puzzled.

“Dad?”

He didn’t respond. He just kept standing there, like he was going to say something. But he wasn’t. I could tell that just by looking at him.

The worst part of it was that he didn’t look like the sleepwalker who’d been at our backdoor, or the one outside the car. His eyes were still aware, still struggling to focus.

“Joyce, if this lab has security, this would be a good time to call for them,” I said, not taking my eyes off my father. He wasn’t moving. I honestly didn’t know whether that was a good sign, or a bad one. In dogs, that sort of stillness could be a precursor to an attack.

“What are you talking about, Sal?” She stepped forward, moving toward us.

I didn’t think. I just reacted, moving quickly to get her out of Dad’s reach. I grabbed her arm and jerked her back just as he began to move again, hands grasping at the air where she had been standing only a half second before. Joyce made a small, startled shrieking sound, one that dwindled almost instantly into a cough. Dad grabbed for the air again. I jerked her even harder away from him.

The other technicians were starting to look up from their work, abandoning the pretense that we could have a private family conversation in the middle of a busy government lab. That was good, since the alternative was their politely ignoring us while my father ripped us apart.

“He’s sick!” I shouted, pulling Joyce another step backward. Dad continued to follow us. At least he wasn’t moving very fast yet; he still seemed disoriented, like he wasn’t sure what to do with himself.

Fight it, Dad, I thought. That… thing… that’s taking you over, fight it for as long as you can. Let me get Joyce out of here.

Joyce finally seemed to understand the danger we were in. She stumbled as she got her feet under her, and then she was backpedaling on her own, no longer relying on me to pull her. “Daddy?” she asked.

“He was fine when we got here!” I said. But that was a lie, wasn’t it? He’d already been slipping, and I’d known that something was wrong, I’d known, and I’d ignored the signs, because… because…

Because I didn’t know what else to do. We were through the broken doors now, and the only ground left was the unfamiliar kind.

Dr. Cale said that once someone started showing symptoms of the sleepwalking sickness, it was too late for any treatment, because the parasite was already in their brain. But she would say that, wouldn’t she? Even if it wasn’t strictly true, she’d say it. The SymboGen implants were her children. She might not actively side with them against the human race. That didn’t mean she was going to go out of her way to figure out how to stop them from taking the things they wanted. Like bodies of their own.