She looked back at him. There was a hint of a smile in her eyes. “Right. I’m also very tired, which isn’t helping my mood any.”

“Understood.”

Joyce seemed a little peppier now. “You want to get going?”

“We’re waiting for Officer Stiebris. He knows the way. He’ll be here in a couple of minutes.”

Joyce nodded. She leaned heavily against the information booth.

“You want some coffee?”Gentry asked. “Maybe a bottle of water? We’ve got a long hot walk ahead.”

She shook her head. “Thanks, though.”

“So, the last day’s been pretty tough?” Gentry asked.

“Yeah.”

“Whatdo you think is going on?”

“I wish I knew. The only universal explanation I can think of is that we’re seeing some kind of bat dementia, though there’s no precedent for it and I have absolutely no idea what could be causing it. The initial lab results from the two patients and the deer carcass came in just as I was leaving. Unfortunately, they don’t tell us very much.”

“What do they tell you?”

“In terms of the two people, nothing more than we already knew. In terms of the deer, only that there’s definitely bat saliva in the blood. But it’s possible the vespers simply lit there-”

“I’m sorry. The who?”

“The vespers. Vespertilionids,” Joyce said. “That’s the breed of bat we’re dealing with.”

“Oh.”

“It’s possible they landed on the deer after it was already dead,” Joyce continued. “But vespers very rarely eat meat, and they definitely aren’t scavengers.”

“Unless they were suffering from dementia, as you said.”

“Yes. Unfortunately, though we haven’t exhausted all the tests, we didn’t find any kind of microbe in the saliva that might cause the bats to act this way. In fact, except for rabies there reallyisn’t a condition we know of that would do this. And rabies wouldn’t cause the kind of-I’ll call it cooperation, for lack of a better word, that the witnesses reported.”

“So you really haven’t got much to go on, have you?”

“No. Though there was something else-what look like several large teeth marks in the deer carcass. They’re about two to three inches long. They look like a mountain lion could have made them, but there were no footprints anywhere. Dr. Nadler made a mold from a gnaw mark in one of the shoulder bones. When Marc is finished at the Central Park Zoo, he’s going to run the mold over to Dr. Lowery at the Museum of Natural History. Maybe he can identify it.”

“I didn’t realize big cats live in the region.”

“They do. The problem is they wouldn’t be strong enough to haul a deer up a tree.”

“Well, I don’t know anything about bats or cats, but I can’t help thinking this deer thing is a prank. Some kind of antienvironmentalist statement.”

Joyce shook her head. “The wildlife commissioner up there said he knows those groups. They print leaflets and bitch on-line. Besides, nobody’s taken credit for killing the deer. But if and when they do, I want to know how they got the damn thing up there.” She looked at Gentry again. “Do you mind if I ask why you’re so concerned about this?”

“Like I told you on the phone, I had a late-night run-in with bats myself. They chased a couple hundred cockroaches from my neighbor’s wall.”

“But you didn’t actually see any bats.”

“That’s right.When I took a look behind the switchplate they were coming from, I found bat guano.”

“How much?”

“I probably could’ve filled seven or eight sandwich bags.”

“Actually, Detective, that’s pretty consistent-”

“Robert,” he interrupted.

“Excuse me?”

“You call me Robert and I’ll call you Nancy.”

“All right,” she said. “Anyway, that much guano is consistent with transient bat habitats in the city’s tunnels and subways. Manhattan has always been a stopping-off point for bats migrating from Canada and New England to the warmer states in the South.”

“It’s funny,” Gentry said. “I never thought of any animals migrating except for birds.”

“Bats do, and for exactly the same reason as birds. Insects are extremely scarce during the winter. Bats usually start the trip in late summer and get where they’re going by midfall.Whenever bats are en route, they’ll usually duck into a shelter to stay cool, eat or drink, stay out of the wind, and hide from predators like cats, hawks, snakes, and owls. That could be the case here.”

“As far as I know, we’ve never had a bat problem or even a bat sighting in my building before.”

“Did you ever have a cockroach problem?”

“Not much of one. And I’m right on the Hudson.”

“I’m not a bug expert, but they could have been chased into your building from somewhere else. A small colony of bats in a subway tunnel might have found a pocket of them. Or they could have been chased in by an upswing in predation near the river.”

Arvids Stiebris arrived as Joyce was speaking. The tall, powerfully built railroad officer clasped Gentry’s hand tightly. Arvids had been a rookie pitcher on the Metro North softball team during the season that just ended. Gentry had played left field from Midtown South and whiffed during three at bats in the last, crucial playoff game. The kid had an unhittable sinker. Robert Gentry was an okay loser and he admired talent, but the “Heroes from West-chester” profile Kathy Leung had done on Arvids really rankled him-“Hartsdale’s gift to Grand Central…and the pitcher’s mound.”

Gentry introduced the officer to Dr. Joyce. Arvids fixed his dark eyes on her.

“I saw you on TV last night with Kathy. That was great spin you put on the bats. Makes you almost want one as a pet.”

“That wasn’t spin, it was the truth,” Joyce said. “If bat diets were compatible with captivity, they’d make wonderful pets.”

“Maybe,” Arvids said. He started toward the ramp that led downstairs. “But I wouldn’t want one unless it was housebroken. That is one potent stench they produce.”

“It’s no worse than that of any other animal,” she replied, “including humans. You’re just not used to it.”

“I’ll take your word for that,” Arvids said.

Gentry thought Joyce was being a touch defensive. But then, he didn’t like it when anyone outside of the department criticized cops. Stereotypes could be frustrating to people who knew better.

“Anyhow,” Arvids went on, “I checked with station maintenance. No one’s been back in the tunnel to clean up the mound. Because this whole thing involved a medical situation, the health inspector has to do an on-site report. You know, tell everyone there’s no danger before they can clean up the guano. That’s supposed to happen later this afternoon.”

“Not that I’m complaining but why are they waiting so long?” Gentry asked.

“They just did a major rat sweep in the north end of Central Park,” Arvids said. “Quiet operation, ethyl chloride-every effective. But a lot of people are still in the field cleaning up the bodies.”

Arvids led Gentry and Joyce to the lowest platform on the east side of the subway terminal. The clerk buzzed them through the service entrance. As they entered and made their way across the crowded ramp, Gentry got the same feeling he’d had earlier-that there was something “off” down here. Subdued. He couldn’t explain why he felt that way.

They walked to the end of the platform. When they reached the far side, Arvids hopped down. Joyce jumped down after him. Gentry sat on the concrete and slid off.

A moment later they were in another world.