“Instead of a dog?” She wrinkled her nose, as if she considered this a less-than-fair deal.

“No, just maybe. One day.”

Darby wore a tight pink T-shirt and jeans with zippers at the ankles. Her dark hair had been swept up to one side of her head and fashioned into a fluffy ponytail. For such a little girl, she had a preening self-confidence. Tess found herself hoping she could hold on to this sense of herself.

“She asked me once if I would like one.”

“Really?”

“On my birthday. I had a party, and I got a lot of presents. Uncle Eric gave me a dollhouse. I still have it.”

“And your mommy said-”

“She said I might have a baby sister or brother before my next birthday. She asked if I would like that. I said I’d rather have a puppy.”

“When’s your birthday, Darby?”

She announced it with the pride that children always reserve for that most important date: “March seventeenth, which is Saint Patrick’s Day.”

It was also, Tess knew, just a few days before Tiffani Gunts had died. She would have asked Darby a few more questions, but Mrs. Gunts came out on the back porch, a kitchen timer in her hand. She had taken the request for five minutes with Darby as literally as possible.

“Will you bring me a puppy the next time you come?” the little girl asked. Her grandparents said nothing, but their anger was so strong it almost came off them in fumes.

They hate me, Tess realized. They would kill this messenger if they could. Because of her, they would have to reinvent the coping mechanisms they had built over the years, revising the stories they had told themselves. The myth of Tiffani was that she was a young woman on the verge of her greatest happiness when a stranger came and took that from her. They did not want to accept this new version because it made the last months of Tiffani’s life a bitter lie. They did not want to admit that her happiness was an illusion. They wanted her to have that brief golden time she had been denied.

But wasn’t the illusion real? If Tiffani believed in her love, then it was true. At least, it was true up to the moment she flicked on the light in her kitchen and stood face-to-face with her perfect boyfriend, the man who had given her everything. And the man who, with one shot to the chest, took it all away.

“It’s something,” Carl allowed, on the drive back to Baltimore.

“I think it’s more than something. I just don’t understand-” Her voice trailed off. Carl wasn’t listening to her, not really. He was tracking something in the rearview mirror, craning his neck at a slight angle.

“What?” she asked.

“I can’t swear to it, but I think he’s back there again.”

“Same car?”

“Yeah. Dark sedan. Foreign.”

“Don’t try to lose him this time,” Tess said, laying a hand on Carl’s arm.

“Why?”

“Let’s see what this is about. Maybe the state police are following us. Or maybe-”

“You think?”

“Anything is possible.”

Carl was in the left lane, moving at a steady clip, slightly above the 65 mph speed limit. He passed another car, but in an unhurried fashion, and then edged into the right lane, only to pick up speed. It was bad driving, but it was a good way to gauge if someone was trying to keep tabs.

“He’s hanging in,” Carl said, “but hanging back.”

“Take the next exit,” Tess said, “but signal this time. Give him a chance.”

Carl did, leaving the highway at a spot that was neither suburban nor rural. The dark sedan followed. Again, the glare made it impossible to see much more than a silhouette at the wheel, and it was too far back to see the front tag. But the car appeared to be a Nissan Sentra.

There was a traffic circle just south of the road leading from the exit. Carl whipped around it so fast that he was almost able to lap the Nissan as it entered. But it handled better on the curves than Carl’s Saturn, and it sped ahead.

“A little faster,” Tess said, “and maybe we’ll be able to see his license plate.”

“What do you think I’m trying to do?” He pushed the car harder, but the Nissan picked up speed too, slipping around the curve, its license plate obscured. Carl pushed the accelerator to the floor and Tess became aware of other cars waiting at the yield signs that led into the circle, scared to merge. She thought the Saturn and the Nissan might end up melting into butter, like the tigers that ran around and around the tree in the old folktale.

But at the next turn, the Nissan shot to the south just as they were overtaking it. Carl couldn’t react quickly enough, so he had to make another full turn around the circle. By the time he had completed the revolution, the sedan was a speck in the distance.

“State cops?” Tess asked.

“I don’t think so.”

“Eric-Alan, keeping a watch on the Guntses’ house, waiting to see if anyone goes there? Or keeping a watch on us?”

“No,” Carl said. “He couldn’t risk that. I know what he looks like, remember? A beard, losing or gaining weight-I spent enough time talking to him to remember him. He can’t afford to get too close to me or to Sergeant Craig.”

“Still-”

“Still nothing. He burns his bridges, this one. He doesn’t go back. He’s done with everything-the place, the women. He wouldn’t go back on a bet.”

They had returned to the highway and were heading toward Baltimore. The roadside views were familiar to Tess now, and she found solace in that familiarity.

“Carl-”

“Yeah?”

“You talk sometimes as if you’re in his head.”

“I’m not,” he said sharply. “And I don’t want to be. I’ve just made a commonsense determination about what he would do, based on what he’s done. He never came back to North East, not even once.”

“He might have-”

“No, I’d have known. People would have gossiped, that stupid newspaper reporter would have called me. I’m not inside him. I’m outside looking at him, the way you’d look at an animal in a zoo.”

“Except he’s not behind bars.”

“No,” Carl said. “He’ll never be.”

“Don’t be defeatist.”

He gave her a quick, level look. “Don’t be naive.”

“What are you saying?”

“When we catch this guy, don’t be surprised if he has to be taken by force. He’s likely to be violent.”

“You’re hoping he’ll be violent.”

“Whatever. We’ll have to protect ourselves.”

“We? You and I? Or the state police?”

“Just don’t be surprised.”

“You’re saying they’ll kill him if they can justify it. Just like that guy in Baltimore County, who they said was going for his gun, only it turned out to be a cell phone.”

“You ever been a member of a SWAT team? You ever gone into a house in the middle of the night to confront a person you know has killed five people and is determined to keep going until he gets what he wants? That’s what that guy in Baltimore County did. Don’t be so quick to make judgments.”

“I’m not. But this guy, our guy-” The plural possessive gave her pause and she lost her train of thought for a moment. “This man, whoever he is, has to be taken alive. How else will we know the entirety of what he’s done? We think he’s killed at least two women. What if there are more?”

“They can work backward. They won’t need his confession to figure out everything he’s done. It’s not like he buries his bodies. He leaves them out in the open.”

“Anyway, it’s a moot point. We’re not going to be there when this comes down. They’re not going to let us get that close.”

“Maybe it’s not in their control. Maybe even as we work the edges of the case, we’re making significant discoveries.”

“Significant? A few minutes ago, you seemed to think the trip to Frederick was a waste of time.”

“It was-until someone tried to follow us. Someone wants to know what we’re doing and where we’re going.”

“I still think it’s the state cops,” Tess said.

“We should be so lucky.”