“That’s digit one,” Joyce said. “The thumb.”

“What happened to the bat?” Gentry asked.

“When I saw it, I was startled,” Lipman said. “I jumped away and the bag spilled over. The bat crawled out.”

“It didn’t fly?” Joyce asked.

“No.”

“Had the wings been hurt in the fire?”

“They didn’t seem to be, but I never saw them spread. The bat crept along the carpet, right here,” he said. “It was maybe nine or ten inches long and it moved slowly, arduously.”

“But it never spread its wings?” Joyce asked.

“No. I wanted to help the poor thing. But when I walked toward it, it vaulted up to the window there”-he pointed to a double window above the couch-“tore through the screen, and jumped out. By the time I went outside, it was gone.”

“Do you have any idea where?”

“I didn’t then,” he said. “I called the wildlife commissioner and told him there was something potentially dangerous out by the Walkill. I wasn’t worried about it being radioactive, but just something alien in the wild. They searched for it up and down the river but found nothing. I didn’t know what happened to it until about a month later.”

“What did happen?” Gentry asked.

“Some hikers found it up the road a way. It was dead. They took a picture of it. I saw the photo in the wildlife section of the local newspaper, and it was unmistakably that bat. Same face, same general build, though it was somewhat desiccated from having been out in the sun. There was one difference, though.”

“It was no longer as bloated as it had been,” Joyce said.

Lipman looked at her. “That’s right. How did you know?”

“Because,” she said, “it was no longer pregnant.”

"I have a question,” Gentry said.

The detective was driving slowly through the early evening dark. The sky was blue-black, and a very bright, clear star was already up in the northwest. Gentry’s goal was a wooded area just off of Route 32 North. Located nearly a mile northeast of Dr. Lipman’s home, that was where the newspaper article said the dead bat had been found. Gentry didn’t know what Nancy expected to find there some eight years later, and she didn’t say. But he agreed that since they were in the area it was probably worth a look.

The young woman was sitting with her knees up against the dashboard. She was holding a rough map the pediatrician had drawn for them on a sheet of prescription paper.

“It’s Jupiter,” Joyce said.

“Pardon?”

“The planet outside your window.”

“What about it?”

“I saw you looking at it. I thought you were going to ask if I knew what it was.”

“No, that wasn’t my question. My dad had been in the navy-he used to point out all the planets and stars.”

Joyce grew slightly embarrassed. She slumped forward a little, into her knees. “Sorry,” she said. “I shouldn’t have done that.”

“Done what?”

“Assumed you didn’t know what that was.”

“Oh, come on. It’s no different from what I did back in the subway, telling you about the third rail.”

“Not many people go walking on subway tracks,” she said. “A lot of people look up at the sky.”

“I didn’t,” Gentry said. “That’s why my dad made a point of telling me about it. About Jupiter and Venus and Orion and Polaris. I was a gutter kid. Bounced balls against the curb, swirled sticks in puddles, fished things out of grates. So ease up on yourself.”

She seemed to, a little.

“If you really want to depress me,” Gentry said, “you’ll know off the top of your head how far it is from the sun.”

She laughed. “About half a billion miles.”

Gentry made a face.

“Hey, I used to be outside a lot at night,” Joyce said. “I wondered about these things so I looked ’em up.”

“You’re amazing,” Gentry said.

“Actually, Robert, what I am is a goddamn smarty-pants. All the kids used to say that.”

“Hump ’em. They were jealous.”

“No, they were kids. Two-legged pack animals. Anyway I don’t want to talk about that. What was your question?”

“What I wanted to know was about radiation. Why is it that radioactivity sometimes causes mutations in living things but at other times it kills them?”

“It has to do with the levels of exposure different cells receive,” Joyce said. “Back in grad school I took a course on the radiogenic effects of artificial and natural toxins on living tissue.”

“Smarty-pants,” he teased.

“I took it pass-fail,” she grinned. “A lot of the physics and chemistry was over my head. But basically there are four ways radiation affects living things. Acute somatic or bodily effects, serious somatic effects, developmental effects, and genetic effects. They depend pretty much on the intensity of the irradiation and the ability of the irradiated tissue to replace damaged cells. For example, skin or the lining of the intestine recovers relatively quickly from lowlevel exposure, while the hair, eyes, and brain don’t recover at all. Rapidly developing fetal tissue-in which the damaged cells can cause a cascade effect that creates damaged cells-are particularly susceptible to radioactivity.”

“Okay, I think I’ve got that. So let’s talk about our big bat. What’s a bat’s gestation period?”

“From three to six months.”

“And how many babies do they have in a litter?”

“Normal bats don’t have litters. They have one or two pups per birth. This particular vespertilionid, I don’t know. Irradiated cells can divide in strange ways.”

“So a high level of exposure could harm a mother and cause mutations in a fetus, but she still might live long enough to carry the pup to term. And the pup might survive.”

“Yes.”

“But then why wouldn’t the pup be radioactive?”

“The radiation isn’t passed along to the child,” Joyce said. “Only the damage.”

“So the mother acts like a filter.”

“In a way. But the changes can be geometric. A mutated child can pass even greater changes on to its offspring.”

Gentry glanced at her. “So a big bat like the Russian one could conceivably give birth to-”

“An even bigger bat,” Joyce said.

“Shit,” Gentry said.

“Yeah. Slow down,” she said as they neared a dark stretch of road. “Up there.”

The route narrowed and ended at a wooded region. Gentry’s shoulders heaved and he sighed.

“Y’know, I can accept most of what you said. But I’m not sure I can make the leap of faith to the next part.”

“Which part?”

“About one or more large predators living out here, in a small town, without being seen.”

“Why not? How often do people see bears up here?”

“That’s different.”

“You’re right,” Joyce said. “A bat can fly. It feeds at night. It has a more diverse diet than a bear or a cougar or a deer. It apparently has a much wider range of predation, which would blunt its impact on the local fauna. And it has the Catskills to the west to prowl around in.”

“Okay,” he said. “It goes unnoticed. Flies too low even to be picked up on airport radar. Then answer one more question.”

“I’ll try.”

“Can you fire a forty-four Magnum?”

She smiled. “Do bats fly?”

“Good. I’ve got two Ruger Super Blackhawks in the trunk,” Gentry said, “and I’m not going mutant bat hunting without them.”

They drove for another five minutes before reaching a clearing. There were no other vehicles in the area. Gentry parked and they got out. He removed the two handguns from the well where he stored the tire jack and grabbed a flashlight from the tool chest. When he closed the trunk, the slam of the door sounded disturbingly final.

It had gotten chilly since they left the doctor’s house. An insistent breeze stirred the treetops, carrying an early hint of fall and a sense of isolation. Branches groaned softly. Gentry heard a train whistle far off. The detective had gone into crackhouses feeling less anxious than he did now. He knew that kind of enemy. The zoned-out junkie or the quick-on-the-trigger pusher. This was something-primalwas the word that came to mind.