Setrakian nodded slowly, then looked back at Eph. “The Master. The root of this evil. Somewhere in Manhattan right now.” The old man looked again at the unfortunate curled up on the floor, who would animate after nightfall, became a vampire, vermin. “You will step back please,” he said, unsheathing his sword. With his pronouncement and a two-handed stroke, he decapitated the man where he lay. As pale pink blood eked out—the host was not yet fully turned—Setrakian wiped his blade on the man’s shirt and returned it to the walking stick. “If only we had some indication of where the Master might be nesting. The site would have been preapproved and perhaps even selected by him. A lair worthy of his stature. A place of darkness, offering shelter from, yet access to, the human world on the surface.” He turned back to Fet. “Do you have any notion where these rats might be rising from? The epicenter of their displacement?”

Fet nodded immediately, his eyes staring into the distance. “I think I know.”

Church Street and Fulton

IN THE DECLINING light of day, the two epidemiologists, the pawnbroker, and the exterminator all stood on the viewing platform on the upper edge of the World Trade Center construction site, the excavation dug one block wide and seventy feet deep.

Fet’s city credentials and one small lie—Setrakian was not a world-famous rodentologist in from Omaha—got them into the subway tunnel without an escort. Fet led them down to the same out-of-service track he had followed before, playing his flashlight upon the ratless tracks. The old man stepped carefully over the ties, picking his way along the bed stones with his oversize walking stick. Eph and Nora carried Luma lights.

“You are not from Russia,” Setrakian said to Fet.

“Just my parents and my name.”

“In Russia, they are called vourdalak. The prevailing myth is that one gains immunity from them by mixing the blood of a vourdalak with flour and making bread from the paste, which must then be eaten.”

“Does that work?”

“As well as any folk remedy. Which is to say, not very well at all.” Setrakian remained far to the right of the electrified third rail. “That steel rod looks handy.”

Fet looked at his length of rebar. “It’s crude. Like me, I suppose. But it gets the job done. Also like me.”

Setrakian lowered his voice to cut down on the tunnel echo. “I have some other instruments you might find at least as effective.”

Fet saw the sump hose the sandhogs had been working on. Farther ahead, the tunnel turned and widened, and Fet recognized the dingy junction at once. “In here,” he said, shining a flashlight beam around, keeping it low.

They stopped and listened to the dripping of water. Fet scoured the ground with his light. “I put down tracking powder last time. See?”

There were human footprints in the powder. Shoes, sneakers, and bare feet.