Back at the B and B, Bernie had returned. I’d asked Lotty whether she should also be taking the antibiotic. Lotty, who usually opposed handing out antibiotics like Halloween candy, said in this case it was essential to err on the side of caution. I handed Bernie her own prescription, explaining the danger.

Her eyes widened. “Dr. Lotty seriously believes that one can become ill from the dirt on that farm?”

“Dr. Lotty is worried about our being around such a lethal organism. You’re going home tomorrow, of course, but on the off chance that I’ve been in touch with whatever the source of the Y. pestis is, she thinks you should take a course of the drug.”

Bernie nodded thoughtfully and took two of the tablets. I poured out the rest of the wine so we wouldn’t be tempted to drink it. Bernie curled up in bed with me to watch To Catch a Thief, a movie designed to make you go to sleep happy. Instead, long after I’d turned off the lights, I kept feeling rats scurrying across the bedclothes. My arms and head itched from phantom fleabites.

In between the antibiotics and Cary Grant, I’d looked up pneumonic plague; the Web confirmed what Lotty had said, that it was transmitted via droplets in the air from an infected person or animal, but my semiconscious mind didn’t believe that. At five-thirty, when I woke gasping for air, sure that pneumonia was clogging my lungs, I gave up on the pretext of rest.

I watched Peppy and Bernie enviously. Peppy opened one eye when I turned on the bedside lamp but fell instantly asleep again when she saw I was only sitting up with my phone, not going anywhere; Bernie didn’t even stir.

I’d texted Aanya Malik as soon as Lotty and I finished speaking, to warn her of the possible cause of Roque’s death: you and ruby and anyone else who’s been in contact with his body should be taking antibiotics prophylactically. She hadn’t responded yet. I hoped that didn’t mean she was already ill, too ill to look at her messages. The gestation period was one to three days, according to the Centers for Disease Control’s website, and Aanya had last seen Roque on Thursday. I looked again at the clock—5:37, too early to call her.

If Dr. Roque had contracted plague and sneezed on the containers he sent Dr. Hitchcock, it’s possible Hitchcock had picked up the disease simply from handling the jars.

But where had Roque contracted it? Not from the baby’s bones: I’d asked Lotty that. Apparently Y. pestis wasn’t as hardy as the anthrax bacillus. It wouldn’t live in the ground or in a corpse for decades, so it couldn’t have been in the soil samples.