“Okay . . .”

“But this is Day Six,” Byron says, and a green dot appears in the far eastern corner of the city. “A new case of the plague is seen way over here. At least six miles away from the other two clusters. This one cannot be linked to Vittoria. Moreover, it’s a skin-related infection with buboes.”

“So it’s not from human-to-human spread.”

“Exactly. Had to have come from an infected fleabite.”

Alana touches the green dot on the screen. “So, either Vittoria and Yasin contracted their original cases of plague over here in the eastern end”—she moves her finger to the red spot by the construction site and draws an imaginary line back to the green one—“or, an animal loaded with infected fleas traveled six miles here from the construction site without infecting anyone in between.” She pauses. “Of course, there’s one other possibility.”

“Which is?”

“There were infected animal vectors in both places.”

“Simultaneously?” He shakes her head. “Not possible. At least not naturally.”

“Not without human intervention, no.”

Byron eyes her for a long moment. “We can assume that one, if not both, of the clusters of infection began somewhere around here in the east.” He taps his finger right next to hers, and they both pull away from the touch. He clears his throat. “There’s a big park around there called Parco Serra Gropallo. Justine is scouring it for rodents. She’s hoping to trap some and test them for Yersinia.”

Her gaze drifts back to the largest of the red glowing points, near where the San Giovanni monastery once stood. “But if the infection really came from the east end of Genoa, then why did someone go to the trouble of sanitizing the construction site of all rats?”

He only shrugs.

Her phone vibrates with a familiar buzz. It’s a text from Sergio, listing a name and an address that Alana asked him to research. She rises from the table. “Let’s go find our monk.”

Byron drives them to the Seminario Arcivescovile di Genova in the heart of the city. She is expecting another Renaissance or Baroque treasure, but the rental car’s GPS leads them to a relatively modern building perched partway up the hill and offering a panoramic view of the old city and the harbor below.

They are met at the entrance of the seminary by a young Hispanic priest whose intentions, Alana quickly realizes, are better than his English. “Arturo Corcione,” she repeats slowly, and, at a loss for an appropriate hand signal, crosses herself. “The abbot of San Giovanni Monastery. Don Arturo.”

A middle-aged cleric, with sunken eyes and a widow’s peak, appears behind the other priest. “I will take you to him.”

“Thank you,” Alana says.

“I am Brother Samuel,” he says as he leads them down a long hallway. “Is the Father Abbot expecting you?”

“No,” Byron says. “We are with the World Health Organization.”

“Ah,” Samuel says, blank-faced.

At the end of the corridor, he ushers them inside a wood-paneled library. The only person in the room is a gray-haired man in a simple black tunic, who looks up from his open newspaper. Samuel speaks to him in a low voice. The older man nods, lowers his paper, and then rises to his feet. “You are looking for me?” He frowns as though puzzled.