“The pustules,” Tim said. “That was the fastest and easiest place to get a sample, so I started there. I collected crawlers from other areas as well, but all of those were dead. And, come to think of it, all of the dead ones look the same as those I collected from Petrovsky.”
Margaret frowned. She reached out, turning the image of the living crawler, looking at it from multiple angles. “Sanchez had pustules, but what was in them didn’t look like these. So we know that Walker definitely had the old kind of crawlers, the ones we saw back in Detroit, the same that are in Petrovsky, but she also had this new kind.”
Tim studied the images on his own HUD. The new crawlers reminded him of a microorganism he’d seen way back in his undergrad days.
“They kind of look like hydras,” he said.
Margaret nodded. “Yeah, a little bit. As good a name as any for the variant.” She stared. The tip of her tongue traced her upper lip. “So the hydras and the crawlers were in Walker at the same time, but only the crawlers were melted.”
Tim watched the real-time image of the hydra, watched it reach and move, searching for something to grab onto. Walker’s crawlers had melted; Petrovsky’s, Sanchez’s and Jewell’s had not. Her hydras were the only known variable.
“Maybe the hydras killed the crawlers,” he said. “Something they secreted, perhaps.”
Margaret thought about that for a moment. “Possibly. But… why? Crawlers and hydras are on the same side, so to speak.”
“Maybe it’s a new design,” Tim said. “The first round of infections — with Perry Dawsey and the other early victims — they only had the triangular growths. But later on, when Detroit got crazy, you saw the crawler-based infections, and even that woman you said blew up like a puffball.”
The look on Margaret’s face made it clear she didn’t want to remember that moment.
“The disease seemed to adapt,” she said. “We stopped the triangles. In the following outbreak the disease expressed itself in at least two new ways.”
Tim closed his eyes, let his brain work through the details, hoping he could find that spark of inspiration. “We’ve had no new activity since the Orbital was shot down. Now we find a piece of the Orbital, and blammo, we’ve a third new form. So it’s reasonable to hypothesize that all the designs originated with the Orbital. You stopped the first attempt, the Dawsey-era infections, so it retooled and tried again with the things you saw in Detroit. You stopped that, so maybe it was already making additional changes when it was shot down. Maybe the hydras are that new design.”
Margaret bit at her lower lip. “Maybe. But that doesn’t explain why hydras would kill crawlers. Why would the Orbital make something that kills something else the Orbital made?”
Tim didn’t have an answer for that. He felt like he was on the right path, although he couldn’t see where that path ended.
“Well, the hydras aren’t an accident,” he said. “The infection reprogrammed Walker’s body to make them.”
Margaret’s eyes stared off, seemed to lose focus. Her lips moved slightly, like she was talking quietly to herself.
“An accident,” she said. She closed her eyes, kept mumbling to herself like a student trying to work out a complex math problem. Tim wasn’t even sure if she knew he was there anymore.
“Tim, what if was an accident. Or rather, a mutation. Maybe there was something different about Walker’s body, about the way her cellular factories reacted to the infection’s reprogramming.” Margaret blinked rapidly, raised her eyebrows — her eyes again focused on him. “Can you get Walker’s medical records?”
“Of course. What do you want to know?”
“Start with her medical history. Maybe there’s something unusual in her system that wasn’t in the other victims.”
Tim called up Walker’s records, scanned through the usual list of military checkups, inoculations, physicals… then found exactly what Margaret was looking for: something unusual.
“She had lupus,” he said.
Margaret shook her head. “That can’t be it. I can’t see how an autoimmune disease would affect the crawlers. They hijack stem cells to produce copies of themselves.”
Tim looked deeper in the record. When he found the next difference, he felt his heart start to hammer.
“Jesus, Margaret… Walker underwent HAC therapy to treat the lupus.”
Margaret narrowed her eyes, not understanding. “What’s HAC therapy?”
That question surprised Tim. She hadn’t just tuned out from life, she’d tuned out from medicine altogether. She wasn’t even reading research journals.
“HAC is human artificial chromosome treatment. It’s an experimental way to treat genetic defects. The process introduces a new chromosome into stem cells. The end result is stem cells with forty-seven chromosomes instead of the normal forty-six that all cells are supposed to have. The forty-seventh chromosome probably has a myriad of immune system modulators meant to reprogram cells to stop the autoimmune effects of lupus — new transcription factors, genetic code to modify gene response, et cetera. In some cases HAC even introduces fully artificial gene sequences.”
Even as he said the words, it struck him how similar the process sounded to the Orbital’s infection strategy: targeted changes to the host’s DNA, altering the processes created by millions of years of evolution. Was humanity that far away from harnessing the very technology that threatened to wipe it out forever?
Margaret’s eyes narrowed. Her nostrils flared. Normally, she looked like she couldn’t hurt a fly, but now her expression was that of a predator.
“An artificial chromosome in stem cells,” she said. “Maybe the Orbital’s technology can’t properly integrate that forty-seventh chromosome.”
She nodded, slowly at first, then gradually faster.
“This therapy,” she said. “Where did Walker get it?”
“Let me check.” Tim read through Walker’s records. “Looks like a clinic within the Spectrum Health System in Grand Rapids, Michigan. Cutting-edge stuff, only ten people in the trial.”
Margaret thought for a moment. Her excitement seemed to grow.
“Correlation isn’t causation, but this is one hell of a correlation,” she said. “We need to see if these new, larger crawlers colonized Walker’s brain, like the older ones colonized Petrovsky’s. Let’s find out right now.”
Tim walked to his prep tray and lifted the compact Stryker saw, preparing to cut into Walker’s skull.
PREPROGRAMMING
Perhaps a thousand modified neutrophils had reached Charlie Petrovsky’s squamous epithelium. Most of them died there, wiped out by the ever-growing apoptosis chain reaction that steadily turned Charlie into a pile of black sludge.
Some, however, held on to life, held on just long enough for a gloved hand to brush against Charlie’s skin.
When that gloved hand moved away, a dozen neutrophils moved with it.
They emitted a new chemical, an airborne signal that announced their presence to any other neutrophils that might be near. If a neutrophil detected that chemical coming from mostly one direction, it moved in that direction: flow, reach, pull… flow, reach, pull. If it detected roughly equal amounts of the chemical coming from multiple directions, it stayed where it was. This simple process created an instant implementation of quorum sensing, of individuals using a basic cue to communicate as a single individual.