“Good, Ms. Butler,” the professor said, and Mary rose her eyes hopefully to meet his. “He watches Letterman. What could this mean? This is an important clue, I think.”

“It could mean that he likes Letterman,” said Brian wryly.

“Or that he hates Leno,” the professor retorted. “But come on. Think here. He is watching Letterman when Polly returns from the going-away party. She watches the show with him and falls asleep and he carries her to bed. What are the possible meanings of that scenario?”

Mary thought. She closed her eyes and tried to find it, to find the truth in the situation. She saw Polly opening the door, coming into the dark house. Polly was a little drunk, stumbling. She put her purse down on the kitchen counter and saw her father. She came into the living room, which was flickering with the light from the TV, and sat beside him on the couch. He put his arm around her. They didn’t say anything because they had the kind of relationship where you didn’t have to speak. Your actions, your gestures, sounds, and tiny movements, told enough of the story of your day.

“He was waiting for her,” she said.

“Why?” Williams asked.

“Because he was worried about Mike.”

“Of course,” the professor said. He was smiling, proud of her for getting there. “He was waiting for her because of Mike. Because there had-what?-been something going on in the last week before she disappeared. Because he was concerned with the old trouble again. Maybe Mike had been coming around again. Does a guy who teaches elementary school children seem to you like a late-night television fan?”

“No,” half the class agreed.

“Are guys with military tattoos normally Letterman fans?”

“No.”

“So what was Polly’s father doing watching television late that night? Of course, he had to be waiting on her. Which means that Mike may have been-may have been-up to his old tricks.”

Williams wrote one more word on the board: retroduction.

“This is a type of logic that suggests that we can account for a truth based on an observed set of facts. It has been proven, or observed, that Polly watched television with her father. It has been observed that Mike and Polly’s father had had run-ins in the past, and that, according to a police report, the two men ‘hated’ each other. It has been observed that Mike physically abused Polly in the past. So we know retroductively, based on Letterman and her father taking Polly to bed, that perhaps he was waiting for her to come in. And thus Mike becomes more of a suspect.”

“It doesn’t fit,” said Dennis then. The familiar light was moving forward, almost to the podium now.

“Mr. Flaherty has an objection!” said Professor Williams. He was still smiling, playing with them, seeing how far they could go with these theories.

“Mike was at the party,” Dennis said.

“He was at the party, yes,” agreed the professor. “Many people saw him that night. That’s what you call a rock-solid alibi. Go on.”

Dennis did not know how to go on. Mary could see the doodles and shapes all over his legal pad, boxes and stars and squares. Dennis had the habit-or perhaps the gift-of listening and not listening at the same time, of being there in spirit and off somewhere simultaneously. Whenever they had been at a restaurant eating, Dennis could look off, his eyes darting here and there, while she spoke. When she questioned him about it, saying, “If you were listening to me, what was I just saying?” he could repeat what she’d said word for word.

“Well,” he finally said, “this means that Mike could not have abducted Polly.”

Another phrase went up on the board: tainted data.

“And why was the data tainted?” the professor asked the class.

“Because everybody at that party was drunk,” Brian said.

“That’s one reason. But there’s something else, something that you don’t know about yet. What was Polly doing that night? Where was she that night?”

“Place,” the girl beside Mary said.

“That’s right, Ms. Bell. Place. And tonight you will find out just a bit more of this intricate puzzle. Be sure to check your e-mail.”

With that, he was through the open door and out of their lives once again.

It was not that Dennis Flaherty regretted doing it. Quite the opposite-he wished that he could do it again. All day he had been craving her, starving for her as if the woman were some kind of sustenance. The only respite had been Dr. Williams’s creepy logic class, but now that he was back in his room at the Tau house, he was feeling it again.

Elizabeth. Somehow her name was more powerful than her body, a body he had roved across for an entire afternoon in the inner sanctum of the old man’s yacht. The old man sleeping above deck, the creek and whisper of the river below them, and Elizabeth teaching him things about himself that he had never dreamed could be true.

The day after the fund-raiser she had called him to ask if he would like to go out with her and the dean to the Thatch River. Her voice was even, almost businesslike, yet it was hiding something. “Sure,” he said. And then, “What is this, Elizabeth?” But she had already hung up on him. It was done. No turning back now.

They had taken out the old man’s cruiser yacht, named The Dante, which he kept in a slip at the Rowe County Marina. Because townies would often break into the marina and damage the boats, Dean Orman had been forced to hire his own man, a retired cop called Pig who circled the parking lot and beamed a spotlight down on the slips every couple of hours or so.

It was one of the last hot-weather weekends, and the lake had been crowded with kids on speedboats. The giant wake of pontoons jarred the old man as he fought with the wheel. They had sailed out toward Little Fork, where you could see Winchester University high up in the trees. “This is where we go,” Dean Orman explained. “It’s quiet here.” They took the yacht back in a cove and anchored it there in the shade.

Orman took the Times up front, where there was some sun cutting a jagged line across the bow. Dennis and Elizabeth went swimming together. They both knew what was going to happen, had been communicating it silently all morning. When the old man’s mouth gaped open, his head tilted back at a strange angle and the Times slack on his chest, they climbed back onto the yacht and crept below deck. There was a little room down there. A bed. Satin sheets that were stiff from weeks of disuse. A musty, stained pillow without a pillowcase. Dennis could barely fit on the bed-he lay on his back with his feet flat on the cold plastic of the boat wall. He was naked and soft. He waited. He told himself that he was doing this for a reason, to finish things with her. It was going to be hard and driving and severe. The boat rocked in the current, and with each rock Dennis’s heart nearly cracked. The old man must surely be waking, coming downstairs to find them.

She stripped off the wet bathing suit and left it in a heap at her jeweled feet. Suddenly, she was transformed. She had shaved her pussy into a little fine arrow of fuzz. Dennis saw in her nakedness a sort of youth, a kind of playfulness he had never seen in their library meetings. How old was Elizabeth? Thirty-five? Forty? He still didn’t know, but she now looked ten years younger than that. She was suddenly achingly beautiful to him, and without really registering what he was doing he was reaching out toward her, touching her, and pulling her down onto him.

But that was the extent of Dennis’s power over Elizabeth Orman. His plan, as Jeremy Price had suggested, had been to pin her down, thrust into her a few times, make it as awful as anything she could imagine so that anything between them after today would be moot. But she would have none of that. She straddled him. And then she began to ride him, her hips matching the sliding, glassy rhythm of the Thatch below them. Dennis wondered: What kind of a woman shaves her pussy? Before he knew it he was coming, losing himself in the frenzied wake, the sloshing sound of the cove now a roar, Elizabeth with her head thrown back on top of him and her tits cupped in her own hands.