“Change of plans, Mr. Armstrong,” Larkin interrupted. “We need to go into the uptown tunnel.”

“You need to go… in the tunnel?”

“Yes. At once. Immediately.”

“Uh… yeah, I don’t… having workers on the tracks disrupts train schedules. It’s gotta be planned in advance. Ms. Crowley might be able to organize getting you in the tunnel between midnight and five o’clock,” Armstrong suggested.

“No,” Larkin said flatly.

Doyle stepped in to explain, “There’s a population of runaways and homeless who have set up a sort of camp somewhere between here and Sixty-Third and Lex. A teen girl among them is wanted for murder, and we believe she returned to this station less than an hour ago.”

Larkin added, “I have probable cause that she intends to kill another individual who’s currently hiding in the system. Now, please pretend this situation is a track fire.”

“The number-one rule on the tracks is, do not touch the third rail,” Armstrong warned, turning the beam of his flashlight on the raised and covered rail. “My dad worked for the Transit Authority in the ’80s. He told me he saw a guy step on the track and explode. Arms and legs literally shot off his core like missiles.”

“Noted,” Doyle said from the rear.

It’d taken longer than Larkin preferred to get to the platform and actually climb down the access stairs into the tunnel proper, but Armstrong didn’t have the sort of authority they’d needed, which required a phone call to Ms. Crowley, the station manager, which turned into a conversation with the Command Center, who then of course looped Lieutenant Connor in on the request, before approval was given to reroute uptown F trains onto the E line from West Fourth due to “police activity.”

Larkin and Doyle had left behind their suit coats in exchange for the same orange safety vest that Armstrong wore, and with pistols drawn and kept at low-ready, proceeded into the tunnel that’d been in twenty-four-hour continuous use for a hundred years. The garbage that’d settled on the tracks was the usual sort—empty soda bottles, napkins, candy wrappers, one uncapped and used needle, and a crust of pizza being hauled into the shadows by a rodent of unusual size. Maintenance lights, their bulbs grimy with dirt and soot and God only knew what else, did little to brighten beyond the immediate steps in front of them, while their flashlights illuminated years of graffiti along the walls. Most of the tags were sloppy, the artist’s name indecipherable, but there were one or two, the deeper they moved uptown, that Larkin almost dared to consider art.

Illegal, certainly, but a sort of beautiful and gritty urban art nonetheless.

“You know,” Armstrong said from ahead of Larkin, “I’m not surprised to hear there’s an encampment in this tunnel.”

“Why do you say that.”