I was wondering when you’d get around to asking about the Mitchell case. She’s a remarkable girl, young Sally. There are some people who think SymboGen saved her life. Well, I don’t feel that I’m bragging when I say that they’re probably right. We were nowhere near the accident, of course, we didn’t find out about it until later, but the presence of her implant made it possible for her body to survive the amount of trauma she experienced. The machines can only do so much, they’re on the outside. An implant, on the other hand… that can work from the inside, it can tailor its response faster than any doctor. It helps that the Mitchell family was able to get a really good, top-of-the-line model for Sally. Colonel Mitchell made sure his entire family was equipped with tailored Intestinal Bodyguards™. That must be what saved her.

SymboGen saves lives. Don’t let anyone try to convince you differently. If you think I’m wrong, well. Why don’t you try asking Sally Mitchell?

—FROM “KING OF THE WORMS,” AN INTERVIEW WITH DR. STEVEN BANKS, CO-FOUNDER OF SYMBOGEN. ORIGINALLY PUBLISHED IN ROLLING STONE, FEBRUARY 2027.

… the core genetic material for the SymboGen Intestinal Bodyguard™ was taken not from T. solium, as many would naturally assume, but from a subspecies of Diphyllobothrium—specifically D. yonagoensis. Many other genetic sources were utilized in the development of the Intestinal Bodyguard™; however, D. yonagoensis provided fully 63% of the initial genome.

By using a species not known for parasitizing humans as a primary host, SymboGen was able to control the life cycle of the Intestinal Bodyguard™ to an unprecedented degree. Their guarantees of sterility and planned obsolescence have thus far been borne out by all independent and internal testing. Their tailored species of Diphyllobothrium, D. symbogenesis, is stable, and genetically distinct enough not to be confused with any naturally occurring genotype, yet is incapable of reproducing itself outside the laboratory environment…

—FROM “THE DEVELOPMENT AND LIFE CYCLE OF DIPHYLLOBOTHRIUM SYMBOGENESIS,” ORIGINALLY PUBLISHED IN THE STANFORD SCIENCE REVIEW, JUNE 2017.

Chapter 2

JULY 2027

It took half an hour to do the litter boxes, and another hour to feed and medicate the kittens in the isolation room. They would be kept away from the rest of the cats until their blood tests came back negative for any infections or parasites; then they would be integrated into the rest of the shelter’s population, to await their “forever homes.” The irony of an organization where every human was a proud parasite-carrier working diligently to cure animals of parasites was not lost on me. Nathan liked to say that SymboGen wouldn’t rest until they’d perfected the Intestinal Bodyguard for use in every animal in America. Then he’d laugh like he was joking, even though we both knew he wasn’t.

I didn’t get the chance to check my phone until I was done with the last cage. There were two messages waiting for me. The first was from my sister, demanding—in her usual, strident Joyce way—to know how therapy had gone, and whether she got to keep treating me like the crazy one. There was a note of genuine concern under her nagging. She knew how much I hated seeing Dr. Morrison.

Nathan had left the second message only a few minutes before. It was substantially shorter than Joyce’s had been:

“Look outside.”

I lowered the phone as I crossed to the window. Nathan’s car was parked across the street. He was sitting on the hood in an easy cross-legged position, elbows resting on his knees as he smiled at the shelter, like he was waiting for me to appear.

I swiped my thumb across his name on my contact list before raising my phone to my ear. He dug out his own phone a few seconds later. “Hello?” he said.

“This is stalker behavior, you know,” I said sweetly. “Only stalkers park outside women’s places of employment and sit there waiting to see if they’re going to come out.”

“I prefer to think of it as being a compassionate, concerned boyfriend who didn’t want to make you take the bus,” said Nathan. “Stalker behavior would have me hiding in the supply closet.”

“What if I was looking forward to riding that bus?” I asked. “What if I’m playing a game of guess-that-smell with the driver, and I don’t want to let him pull ahead of me as we approach the championship round?”

“I suppose I’d just have to slink sadly back to my empty apartment, no girlfriend in my car, no one to go out to dinner with me,” said Nathan, and sighed theatrically. “I’ll just sit there in the dark, all alone…”

I laughed. “You’re a ham. You’re an absolute ham.”

“Probably true, and good use of the word ‘ham,’ ” Nathan replied, the faux mournfulness gone in an instant. “Come down, Sal. I’ll give you a ride home, and you can tell me how your appointment with Dr. Morrison went.”

“Do I have to?”

“Come down? Sure, unless you want to live at the shelter—a valid lifestyle choice, I admit, but probably boring in the long run.” Nathan paused before adding, “We don’t have to talk about Dr. Morrison if you don’t want to. I just thought you might.”

As soon as he said it, I realized that he was right: I did want to talk about it. I didn’t want to go home and try to sleep with all that rattling around my brain. “I’ll be right down,” I said, and hung up.

Tasha was gone when I emerged from the back. Will was still there, sitting at the front desk. The cat from before was sitting next to the computer, nonchalantly washing a paw. It looked up when I entered the room, flicking its tail once. The tail landed across the keyboard, and Will looked up.