Oker’s confirmed it. The cure caused the real pandemic.

“I’ve gotten ahead of myself,” Oker says. “I haven’t yet told you the way a virus works. You’ve figured some of it out for yourself. But the best way to explain it,” and his tone is dry, “is to refer to a story. One of the Hundred, in fact. Number Three. Do you remember it?”

“Yes,” I say, and I actually do. I’ve always remembered it because the girl’s name—Xanthe—sounds a little like my own.

“Tell it to me,” Oker says.

The last time I tried to tell a story was to Lei and it didn’t go well at all. I wish I’d done better for her. But I’ll try again now, because Oker asked me to do it and I think he’s going to be the one to figure out the cure. I have to try to keep from smiling. It’s going to happen. We’re going to do it.

“The story is about a girl named Xanthe,” I say. “One day she decided she didn’t want to eat her own food. When the meal delivery came she snatched her father’s oatmeal and ate it instead. But it was too hot, and all day long Xanthe felt sick and feverish. The next day she stole her mother’s oatmeal, but it was too cold, and Xanthe shook with chills. On the third day she ate her own meal and it was just right. She felt fine.” I stop. It’s a pretty stupid story, meant to remind Society kids to do what they’re told. “It goes on and on like that,” I tell Oker. “She ends up with three citations for improper behavior before she realizes the Society knows what’s right for her.”

To my surprise, he nods. “Good enough,” he says. “The only part you forgot was the part about her hair.”

“Right,” I say. “It was gold. That’s what the name Xanthe means.”

“Doesn’t matter anyway,” Oker says. “The important thing is the idea that something could be too hot, too cold, and just right. That’s what you need to remember about the way a virus works. It uses something I think of as the Xanthe strategy. A virus doesn’t want to run out of targets too quickly. It kills the organism it infects, but it can’t kill too fast. It needs to be able to transfer to another organism in time.”

“So if the virus kills everything too quickly,” I say, “it’s too hot.”

“And if it doesn’t move to another organism fast enough, it dies,” Oker says. “Too cold.”

“But somewhere in the middle,” I say, “is just right.”

Oker nods. “This mutation,” he says, “was just right. And not only because of the Society and the Rising and what they each did. They contributed to some of the conditions, yes. But the virus mutated on its own, as viruses have done for years. There have been Plagues all through history and that won’t end with this one.”

“So we’re never really safe,” I say.

“Oh no, my boy,” Oker says, almost gently. “That might be the Society’s greatest triumph—that so many of us ever believed that we were.”

CHAPTER 31

CASSIA

I should go to see Ky.

I should stay here and work on the cure.

When I let myself really think, I am torn between two places and become lost, adrift in worry, accomplishing nothing and helping no one. So I don’t think, not that way. I think about plants and cures and numbers and I sort through the data, trying to find something that will bring back the still.

Comparing the lists isn’t as simple as it sounds. They don’t only include names of the things that the villagers and the farmers ate, but also the frequency with which the foodstuffs were consumed; the type of ground where they were cultivated, if they were plant or animal goods, and a myriad of other information that needs to be taken into account. Just because something was eaten often doesn’t mean that it provides immunity; conversely, something eaten only once is unlikely to produce immunity.

People go in and out—medics examining patients and returning to report, Oker and Xander doing their work, the sorters taking breaks, Leyna checking in to see our progress. I become accustomed to the comings and goings and eventually I don’t even look up when I hear the wooden door opening, closing; I barely notice when the mountain breeze slips in and rustles my hair.

A woman’s voice breaks into my concentration. “We thought of a few more things,” she says. “I want to make certain we included them all on our list.”

“Of course,” Rebecca says.

Something about the woman’s voice seems familiar. I glance up.

She looks older than her voice sounds, her hair completely gray and twisted in complicated braids and knots up high on her head. She has weathered skin and a gentle way of moving her hands, holding up a list on a piece of paper. Even from here, I can tell that it’s handwritten, not printed.

“Anna,” I say out loud.

She turns to look at me. “Have we met?” she asks.

“No,” I say. “I’m sorry. But I’ve seen your village, and I know Hunter and Eli.” I want to see Eli. But because I’ve been visiting Ky and working on the cure, I haven’t taken the time to go looking for the farmers’ new settlement, even though I know it’s not far from the main village. Guilt washes over me, although I don’t know if Leyna and others would let me go, even if I asked. I am here to work on the cure.

“You must be Cassia,” Anna says. “Eli has always talked about you.”

“I am,” I say. “Tell Eli that Ky is here, too.” Has Eli told Anna about Ky? From the flash of recognition in Anna’s eyes, I think that Eli has. “But Ky is one of the patients.”

“I’m very sorry,” Anna says.

I grip the edges of the rough-hewn table, reminding myself not to think too deeply of Ky, or I’ll break down and be no good to him at all. “Hunter and Eli—they’re fine?”

“They are,” Anna says.

“I’ve wanted to come see them—” I begin.

“It’s all right,” Anna says. “I understand.”

Rebecca moves slightly and Anna takes the hint. She smiles at me. “After I’m finished, I’ll tell Eli that you’re here. He’ll want to see you. And so will Hunter.”

“Thank you,” I say, not quite believing that I’ve met her. This is Anna, the woman who I heard about from Hunter and whose writings I saw in the cave. When she begins reading her list, I can’t tune out the sound of her voice.

“Mariposa lily,” Anna says to Rebecca. “Paintbrush flowers, but only in small quantities. It can be toxic otherwise. We used sage to season, and ephedra for tea . . .”

Words as beautiful as songs. And I realize why I knew Anna’s voice. It sounds the smallest bit like my mother’s. I pull a scrap of paper toward me and write down the names Anna says. My mother might already know some of them, and she will love to learn the others. I’ll sing them back to her when I bring her the cure.

“It’s time for you to rest for a little while.” Rebecca presses a piece of flatbread wrapped in cloth into my hand. The bread is warm and the smell of it makes my stomach rumble. They make their own food here. What would that be like? What if I had time to learn that, too? “And here,” she says, handing me a canteen. “You should eat while you visit him.”

She knows where I’m going, of course.

As I walk down the path to the infirmary, I breathe in the forest. Wildflowers grow in all the places where people don’t walk; purple and red and blue and yellow. The clouds, a stirring and startling pink, soar in the sky above the trees and peaks of the mountains. And a conviction comes to me in this moment: We can find a cure. I have never felt it so strongly.

When I arrive, I sit down next to Ky and look at him, touch his hand.

The victims of the Plague don’t close their eyes. I wish that they did. Ky’s look flat and gray; not the colors I’m used to seeing, blue, green. I put my hand on his forehead, feeling the smooth expanse of skin and the understructure of bone. He seems hot. Could he be infected? “He doesn’t look good,” I say to one of the medics on duty. “His nutrient bag is already empty. Do you have the drip turned up too high?”

She checks her notes. “This patient should still have one working.”

I don’t move. It’s not Ky’s fault something went wrong. After a moment she stands up and goes to get a new bag to attach to his line. She seems harried. There are only two medics on duty. “Do you need more help in here?” I ask.

“No,” she says sharply. “Leyna and Oker only want those of us with medical training to work with the still.”

After she finishes, I sit next to Ky and rest my hand on his, thinking of how alive he was on the Hill, in the canyons, and, for a moment, in the mountains. And then he was gone. I think of how I spent all that time puzzling out the color of his eyes when I started to fall in love with him. I found him changeable and difficult to put into one finite set, one clear description.

The door opens and I turn, expecting to see someone coming to tell me that my time’s up, that I need to return to work. And I don’t want to leave. It’s strange. When I was sorting, I felt certain it was the most important thing I could be doing. When I’m here, I know that being with the still matters most.

But it’s not someone from the research lab. It’s Anna.

“May I come in?” Anna asks. After she’s washed her hands and put on her face mask, she comes toward me. I stand up, ready to offer her my chair, but she shakes her head and sits on the floor near the bed. It’s strange to be looking down at her.

“So this is Ky,” she says. He’s turned on his side and she looks into his eyes and touches his hand. “Eli wants to see him. Do you think it’s a good idea?”

“I don’t know,” I say. It might be a good idea for Eli to come because then Ky could hear more than only my voice speaking to him, calling him back. But would it be good for Eli? “You would know better than I.” It’s hard to say, but of course it’s true. I only knew Eli for days. She has known him for months.

“Eli told me that Ky’s father was a trader,” Anna says. “Eli didn’t know his name, but he remembered that Ky told him his father learned to write in our village.”

“Yes,” I say. “Do you remember him?”

“Yes,” Anna says. “I wouldn’t forget him. His name was Sione Finnow. I helped him learn to write it. Of course, he wanted to learn his wife’s name first.” She smiles. “He traded for her whenever he could. He brought her those paintbrushes even when he couldn’t afford paint.”

I wonder if Ky can hear this.

“Sione traded for Ky, too,” Anna says.

“What do you mean?” I ask.

“Some of the traders used to work with the rogue pilots,” Anna says. “The ones who flew people out of the Society. Sione did that, once.”

“He tried to trade to get Ky out?” I ask, surprised.

“No,” she says. “Sione executed a trade on another’s behalf to bring someone—his nephew—to the stone villages. We farmers never assisted in any of that, of course. But Sione told me about it.”