“I’m grateful, of course,” he said, his face reflecting anything but gratitude. “But . . .” I glanced at him, waiting for the other shoe to drop. This conference was chock-full of M.D.s, Ph.D.s, M.P.H.s, and people with obscure military titles; they constituted some of the most powerful people in Washington and Atlanta. None of them looked as if they possessed a sense of humor. Wally, on the other hand, was renowned for his practical jokes. Once, on an EIS investigation of a mysterious sickness at the Republican National Convention (nonlethal; non-terrorism), he’d sent the team a box that turned out to contain three tiny mechanical elephants that marched around trumpeting to the tune of a popular country music song until, suddenly, they fell over and died with their legs sticking straight up. This was in poor taste, but it paled in comparison to some of his other pranks. How Wally had survived the quasi-militaristic bureaucracy of the EIS followed by the bureaucratic bureaucracy of the CDC without getting himself sacked, or at the very least reprimanded, was a mystery for the ages.

“But I won’t be needing security,” he finished, more or less harmlessly. I breathed a sigh of relief as he twirled the Molestache. “I am not the kind of person who can function with an entourage.”

“You will both have a security detail,” said the COO, with no inflection in her voice whatsoever. That concluded the discussion on this topic; the conversation moved on to something else, leaving Wally sitting there with his mouth open.

Now, in October, the promised escort had never quite materialized. The powers that be eventually agreed we were not at particular risk within the confines of the CDC itself. When Wally and I were at work, we could roam free. Whenever we set foot outside the building, however, we were supposed to gain a shadow, but after a few weeks of promises, the expense had become too burdensome or the horde of potential anti-vaccine assassins had never materialized or, most likely, someone in the government had realized neither of us was particularly recognizable or even interesting to the public, and the idea of a security detail had melted away.

Next to mine, a door shut. Wally, his arms full of reams and reams of paper, stepped into the hall. “Hey there, tree killer,” I said.

Wally looked up, startled. In contrast to the buoyant young man who’d passed by a second ago, all of Wally’s features had taken on a droopy cast. His shoulders slumped. His eyelids were fixed at half-mast. Even his mustache had shed its Tom Selleck vibe and now ran more along the lines of what you’d expect on a very sad walrus. He held his breath, lodged his cache of papers under an armpit to free up a hand, and yanked up his mask to cover his mouth.

“I don’t like reading on screens,” said Wally, mournfully but loudly.

“Oh, Wally,” I said, alarmed. “You look terrible.”