I stared at him as I sat down in one of the chairs across from his desk. I knew SymboGen had been watching me. I still somehow didn’t expect him to be quite so open about admitting it. “But…”

“Please listen to me very carefully, because it’s important to me that you understand: the sleepwalking sickness is the result of a different parasitic infection.”

“What?”

“It’s my fault. I pioneered the idea that parasites were our friends, that they could somehow be tamed and turned from enemies into allies, and I caused this. People stopped being as careful as they needed to be.” Dr. Banks raked a hand through his hair, mussing the normally perfect strands still further. “It’s funny, in a horrible way. We were trying to prove the hygiene hypothesis was something that could be beaten. What we didn’t anticipate was people turning ‘nothing in nature can hurt you’ into a gospel.”

I was still staring. The words I needed to question him just weren’t there.

Apparently, Dr. Banks had been waiting for a willing audience, because he kept on going. “Off-brand parasites have become an increasing problem recently. They’re all black market, of course—I’m not too proud to admit that we’ve greased the wheels at the FDA to keep any competitors to the implant from seeing the light of day—but they’re still out there. People are messing with the genome of anything they think might turn a profit. And because there’s a sucker born every minute, those profits can be substantial.”

“Chave didn’t pick up any off-brand parasites.”

“No, she didn’t. She was a company woman, through and through, and I miss her more than you can possibly know. You saw her when you deigned to visit us—oh, don’t look so shocked, Sally. I know you hate coming here. It’s why I was so surprised to see you today—but I saw her every day. She managed my schedule. She knew everything about me, and she didn’t judge me for any of it. Now, if you really think I have a treatment, can you think of any possible reason that I would have refused to share it with Chave?” He shook his head. “I’m not a monster, Sally. This might be easier if I were. This might be easier on everyone.”

“So the sleepwalking sickness is parasitic, but it’s not a SymboGen parasite?”

“Now you’re catching on. We think that whoever created the parasite that causes it wanted to make something small—something that wouldn’t catch the attention of the implants. They’re very territorial, you know, and they won’t tolerate the presence of a competing parasite. So these unknown engineers started with a protozoa parasite, and worked their way up from there. The trouble is, protozoa can be transmitted in water. And most modern filtration systems haven’t been constructed to filter out parasites. It would be a waste of money.”

The chain of transmission he was proposing made sense. People ingest illegal, black market parasites for some reason—and let’s face it, there are always people willing to do things that seem stupid if they think they’re going to get something out of it—and then those parasites find their way into shower drains and sinks as their new host’s body adjusts to their presence. Once they got into the water, the parasites would be able to sail right into the body of another host, with no one the wiser. I wasn’t sure how big protozoa were, but they’d have to be pretty small if they were designed not to attract the attention of the implants.

“Wouldn’t the protozoa be territorial?” I asked.

“Not in the same way,” he said, sounding more confident now, like I’d finally ventured onto territory he knew how to manage. “Tapeworms are generally solitary, because they have to be; very few hosts can support two healthy adult tapeworms without dying. Even so, in nature, it’s not unusual for people to have multiple tapeworms, because they’re hermaphrodites, and sometimes their babies just don’t go looking for places of their own.”

The fact that he was making jokes, even terrible ones, made me want to claw his eyes out. I forced myself to remain still. “So these protozoa, they’d come in groups? And that way, if some of them got out of the body, there would still be protozoa in their original hosts?”

“Yes, exactly. We believe that what’s happening—the most reasonable chain of transmission—is fools looking for a magic bullet ingesting the generation one, or G1, protozoa. Once their infection is established, they start shedding excess parasites into the water supply, where they reproduce, creating generation two, or G2, protozoa. From there, the G2 protozoa make their way into faucets and showers, and gradually spread the infection.” Dr. Banks shook his head. “What’s truly tragic about this is that it seems likely that the people who started this whole mess are the only ones not getting sick. Having a pre-established G1 colony is likely to protect them from the encroaching G2 colony, and it seems likely that only the G2 protozoa are actually causing their hosts to succumb to the sleepwalking sickness.”

“Oh.” My head was starting to spin from all the scientific jargon he was spouting. I desperately wished that Nathan was there. He’d have been able to tell me how much of this was real and how much was carefully created spin doctoring, using possibilities and potentials to craft a story that sounded almost plausible. “So how much of this do you know? I mean, you keep saying ‘we think’ and ‘we guess,’ but you haven’t said very much ‘we know.’ How much have you proven?”