He tells her about Ophiocordyceps unilateralis, the rain-forest fungus that infects the bodies of ants and saps them of nutrients and pirates their minds. The ant becomes fully possessed over the course of a week, and during that time, it seeks out an ideal temperature and humidity for incubation—what turns out to be a height of twenty-five centimeters. Here it latches onto a leaf near its colony. A stalk of fungus then splits the ant’s head and the spores spill down onto the other ants, infecting them.

Not only are there approximately 3.8 million different types of fungi in the world, but fungus finds a way to kill around 1.5 million people every year.

“But have you ever heard of a fungus that causes behavior like this?” she says, and he says, “No. That’s why I need a sample to study.”

“I can’t believe we’re talking about murder as a contagion,” Nora says, and their eyes meet and settle into a stare. “We’re saying that, aren’t we? That murder is catching.”

“Is it murder, though?”

She feels that old flash of annoyance at his question. It could be such a classic Jack throwaway comment, since he’s so often like the jackass kid in ninth grade who’s always trying to rile the teacher: Can you actually cry underwater? Why does a round pizza come in a square box? Is soy milk just milk introducing itself in Spanish? But his tone appears genuine, so she tries not to make her voice too biting when she says, “What else would you call this?”

“You’re a cold person. Just think about it in coldly scientific terms.”

“Oh, I’m a cold person?”

“Yes. That’s not a judgment.”

“How is that not a judgment?”

“Because a fact is not a judgment. Has a commercial ever made you cry? Do you ever ask if you can pet other people’s cats or hold their babies?”

“Cats are creepy.”

“Do you find Christmas annoying? Do you call friends to check up on them?”

“Who just saved your ass?”

“I’m grateful!” He holds up his hands as if she’s aiming a gun at him. “I’m not saying you’re not a good person. I just mean—let me rephrase what I mean. Forget the emotions behind all of this. Forget the so-called rightness and wrongness. Because morality is irrelevant to the natural world. Mistletoe siphoning nutrients off a balsam tree isn’t wrong. A lion chasing down a gazelle isn’t wrong. So neither is a fungus killing someone. It just is what it is. And if something has to die for something else to grow, then so be it. That’s the law of the jungle.”

“Maybe you’re the one who’s cold.”

“Hey, I cry during commercials all the time. I will pet the shit out of somebody else’s cat. And I fucking love Christmas.”

“Well, you’re still wrong,” she says.