When Gentry felt better, he opened his eyes, breathed one more time through his teeth, then walked slowly down the steps toward the third level.There were no more victims there and no bats. Only drops of blood that had seeped through the grate.

Returning to the second level, Gentry went to each of the bodies in turn. He wanted to make certain that everyone was dead. Not just so that he could help anyone who might still be alive but also to make sure that one of the bodies wasn’t a psycho pretending to be dead.

There was no one left alive.

As he stood and backed away from the corpses, Gentry noticed that there was artwork spray-painted on the far wall. Not-bad portraits and a panorama of bright blue sky. Tucked into corners of the room were garbage bags stuffed with clothes; pieces of carpet were spread under some of the sleeping bags. These people obviously lived in this part of the underground. They weren’t intruding in a bat area like the people in Westchester.

The bats had come here wanting something. And then there was the woman in the bicycle helmet. He turned and looked down at her. He didn’t want to search for an ID until the forensics team had a chance to take photographs. But he wondered where she fit into all of this.

As he looked away, he suddenly noticed a thick trail of blood. It began about a foot from the dead woman’s left ear and thinned the closer it got to the landing. It continued up the steps in closely spaced dollops.

That’s where the blood on the steps came from, he realized. But there was something odd.

Gentry crouched and looked at the blood more closely. The trail thinned as it went up, as though it had been drippingup the steps. Which meant the killer did this and then left by the stairway. It was also a slow, thick, steady drip, which meant it probably wasn’t made by a creature in fast flight. He wondered if that ruled out a bat as the killer.

He turned the flashlight up.

“Oh, shit,” he said.

There was blood on the underside of the grate above him. It was left in hash marks all along the grate. They looked like large chicken scratches.

Or bat scratches?he wondered.

What seemed curious,though,was that the bloody marks above were thicker than the ones below. And they followed the trail on the stairs exactly-

Like they dripped down.

And then it hit him, though it didn’t make sense. Someone, something, could have left this way without using the steps.

The killer could have been hanging from the grate.

Gentry went back to the main tunnel to call for assistance. Captain Moreaux told the detective that they’d get a team down as soon as possible.

Gentry asked if he knew where Nancy Joyce was. Ari told him that she’d gone up to the Museum of Natural History.

That made sense. It was where her assistant had taken the mold from the deer bone.

Feeling guilty again, the detective went back to the walled-off sublevel. He sat on the landing and looked into the room. The only sound was the occasional distant thunder of a subway train.

It was difficult for him to process the horror of what had happened down here. The pain. The speed-these people were slaughtered where they lay. But it also underscored what he had always believed,despite the years his father had made him go to church. That human beings are animals. Not just the perpetrators but the victims. The reverential funerals and talk about immortal souls notwithstanding, people inevitably bear an unnerving resemblance to beef.

Captain Moreaux arrived nearly half an hour later, with Arvids and four other officers from Metro North. Two of the men got sick. In the heat, the smell was becoming intolerable. The officers were joined by three transit police-under whose jurisdiction the subways typically fell-and five officers from the police Emergency Service Unit. This mobile force of 350 elite officers is not attached to any one precinct. They’re divided into ten regional squads and are called in to assist precinct police in extreme situations ranging from hostage standoffs to river rescues.LieutenantGary Holmes of ESU, City South, was at the end of his two-to-ten shift when he arrived with his team.

Gentry stayed for a while in what was already being referred to as “the butcher shop.” Police were always quick to assign lighthearted nicknames to places of violence or danger. This was done not out of disrespect but, Gentry believed, to give them a way of denying the extreme horror until the situation could be dealt with and processed.

A Metro North police officer photographed the scene before ESU officers began placing the bodies in bags. While Gentry watched from the landing, two officers gently searched the outside woman’s body for identification. They found a blood-soaked pouch beneath the body, attached to her leather belt. Her wallet was inside, along with a can of mace, a Swiss army knife, and an I Love New York key ring. No money had been taken. Arvids looked at her driver’s license. The woman’s name was Barbara Mathis and she lived on Riverside Drive. She was smiling in the photograph and attractively made up. She was twenty-eight years old. About the same age as Dr. Joyce.

Most of the bodies would be taken to the city medical examiner. Before they were removed, Gentry went over to Captain Moreaux.

“Ari, I need you to do me a favor. I want you to take Ms. Mathis’s remains to the Scientific Research Division.”

“Chris Henry?”

Gentry nodded.

Moreaux winced. “Ouch. The medical examiner will not be pleased if I do that.”

“I know. But the medical examiner is going to have his hands full with the tunnel people. This lady came from someplace else.”

“Obviously-”

“I need to know where and I need to know it soon. Chris’ll do this fast and right.”

Moreaux thought for a moment. “Okay. I’ll go set it up.”

Gentry thanked him. Moreaux looked pale as he took the wallet and went back to his office. The captain was the one who was going to have to call the young woman’s family.

Before leaving, Gentry went over to Arvids and thanked him for his help. Then he started up the stairs.

“Detective,” Arvids said.

Gentry stopped and looked back.

“I just thought you should know that Dr. Joyce was still pretty steamed when she left.”

“I’m not surprised. And I don’t blame her.”

“What I’m saying is, maybe you should talk to her. Keep her in the loop. She wants to help. And this”-he gestured behind him-“is gonna take some explaining.”

“Don’t worry, Arvids. I’m going to involve her.”

Arvids thanked him. Gentry wondered what the hell that was really about.

It was much easier getting out of the tunnel than it had been getting in. In order to accommodate the evacuation team, subway traffic had been rerouted along the tracks leading to the underground rooms. The detective was surprised at how cool and clean the air tasted and how bright the daylight seemed when he reentered the terminal. The concourse was much less crowded than it had been before.

Gentry stopped at a pay phone and called Chris Henry. He told him to expect Barbara Mathis’s body within the hour and to front-burner the autopsy. He wanted to know as soon as possible whether the woman had been sexually assaulted and if there was anything on her that would place her whereabouts at the time of her death-dust particles in the lungs or eyes, muffin crumbs in her mouth, anything. Henry thanked him and said he’d be back to him as soon as possible.

As he left Grand Central, Gentry’s mind was on the bats. As he walked west toward the station house, he wondered whether the attack and possible infestation were going to be a small problem or a big one; or whether it was a small problem that would become a big one when the media got their teeth into it. Nancy had been right about one thing. He wished he knew more about bats. Unlike human perps, he had no way of knowing what, if anything, they were going to do next. That was frustrating.