I blinked. “Da—Colonel Mitchell isn’t epileptic, and neither am I,” I said. “The seizure Sally had right before her accident was the only one she’d ever had.”

“No, the seizure Sally had right before her accident was the only one she’d ever had on camera,” said Dr. Cale. “Colonel Mitchell couldn’t bury that one, since it was in the news, but it got mostly overlooked in the face of everything else that was unusual about your case. Sally was our canary in the coal mine, and you were our bellwether. You told us what was coming just by showing up. What’s more, you told us where we should be looking for more like you.”

I frowned. Nathan frowned. Adam, however, wasn’t so easily distracted by irrelevant points of science. “You took out part of Sal without her permission?” he asked, frowning deeply.

I glanced at him, surprised. He’d been quiet for long enough that I’d almost managed to forget that he was there.

Dr. Cale nodded, expression solemnly regretful. If there had been a competition for looking most sorry about something you weren’t actually sorry about, she would have won instantly. “I did, but sweetheart, I didn’t want to open up her skull twice, and we had to act quickly. There wasn’t time for a discussion.”

“Would you take part of me out without my permission?”

“No, of course not. But darling—”

“She couldn’t risk me saying no,” I said, in that cold, alien voice. “It would have ruined her plans, since then she couldn’t have used Nathan to help her work the samples. He would never have allowed her to do what she did, if he’d known.”

“That’s right,” said Nathan. “I wouldn’t.”

Dr. Cale turned to frown at both of us. “I told you, I needed—”

“No means no, Dr. Cale,” I said.

“Sal’s my sister,” said Adam fiercely. “You should be as good to her as you are to me, and that wasn’t very good to her at all. You shouldn’t have done that.”

“He’s right,” I said. “You shouldn’t have done it, and I’m never going to trust you like that again. But you learned what you needed to know?”

“Some of what I needed to know,” said Dr. Cale.

“Then I guess that makes it all better,” I said, putting a sarcastic twist on the last two words that actually made her mouth purse in something I didn’t recognize, but that I hoped was shame. I put a hand against my forehead, wishing I had some way to quiet the drums that were pounding in my ears. “I have a headache, and I miss my dogs. Can I go to wherever it is they are now, please? I just need to see them, and then you can tell me whatever else it is you’ve learned by taking pieces out of my head.”

“Come on, Sal,” said Nathan, slipping his hand back into mine. It fit perfectly. “This way.”

“Adam, I’ll come see you soon, okay?” I said. My brother nodded, still looking troubled by what his mother had done to me. Good. It was better if she didn’t start thinking this sort of thing was okay.

“It’s good to have you back, Sal,” said Dr. Cale.

“It’s good to be home,” I said, and let Nathan lead me away.

Nathan led me back to the elevator, this time pressing the button for the top floor. I leaned against him, feeling my entire body start to tremble. The events of the morning had been too much for me, especially after spending weeks in the mostly low-stimulus environment of Sherman’s mall. By the time the elevator stopped I was shaking so hard that I could barely walk. Nathan put his arm around me, holding me up as I half stumbled out of the elevator and into the hall.

“Do you need me to carry you?” he asked.

I thought about the question seriously before I nodded and said, without a trace of shame, “Yes, please.” The idea of taking another step made the drums pound even harder, a sure sign that I was stressed beyond my breaking point.

Nathan bent and scooped me into his arms. I’d lost weight and he’d gained muscle, our respective paths through the apocalypse leaving their marks on our bodies: he couldn’t have carried me like this before we were separated. “This used to be the research and development floor,” he said, carrying me past door after door. Each of them was painted in a different, clashing candy color. “I don’t know why they put the labs here on the top floor. It may have been a ventilation issue, or maybe they just wanted the place to burn from the top down if there was ever an accident.”

I couldn’t help it: I laughed a little at the image of some architect seriously explaining that they’d put the fire hazards all in one place for insurance reasons.

Nathan smiled. “The labs are small enough that we’ve been converting them into living quarters. Most people are double-bunking it, but I was able to convince Mom that I should have a lab to myself until you came home, rather than having a temporary roommate. I didn’t want there to be any delay when you got back.”

“Thank you,” I said, leaning up to kiss his cheek.

“Don’t thank me yet; it’s another bachelor apartment for you to judge me by,” he cautioned, stopping in front of a violently magenta door. It was unlocked. I blinked, and he stopped with his hand still on the doorknob, explaining: “We keep all rooms unlocked when they’re unoccupied, to make it easier for the staff to find shelter in the event of a sleepwalker outbreak inside the facility.”