Swann got up from the bench, turned on the detector. It was show-time. He walked along the side of the road, brow furrowed, deep in concentration. When he positioned himself about twenty yards behind the girl, the detector alerted him. She heard, turned to watch.

“Yes!” he exclaimed loud enough for the girl to hear. “Oh yes, yes, yes.”

Out of the corner of his eye he saw her considering him. Who was this strange man with this strange machine? Her teenage curiosity could not resist.

“Did you find something?” she asked.

He looked up, around, as if trying to determine from where the voice had come. He found her, pointed to the ground near his feet. “Eureka!”

Swann bent over, picked up a necklace. The necklace was cheap gold. It had been palmed in his hand the whole time. “I struck gold!”

He held it up. The necklace glittered in the morning sun. The girl got up to take a closer look. They always did.

“Oh man. Sweet,” she said. “Very cool.” Her eyes went from the necklace to the emblem on his jumpsuit. The patch looked official, as if he were part of the park service. Closer scrutiny would reveal nothing of the kind.

“You didn’t lose this by any chance, did you?” he asked, slight disappointment edging his voice.

The girl hesitated for a moment—Swann would have been deeply disappointed if she had not, the longer she hesitated the longer she had been on the road—then shook her head. “No. I wish. It’s really nice.”

Swann put the necklace into his bag. “You’d be amazed what I’ve been able to find over the years.”

“I’ll bet.” She shoved her hands into her jeans pockets. She wanted to talk. She was lonely. “What kinds of stuff?”

“Gosh, let’s see. Rings, bracelets, coins, barrettes. Lots and lots of barrettes.”

The girl laughed. “Kids.”

“Tell me about it. I buy my daughters barrettes by the case. They are always losing them.” He turned off the machine. “My name’s Ludo, by the way.”

“Ludo? Cool name. Mine’s Claire.” They shook hands. He did not remove his gloves. “Do you work here?” she asked.

“As little as possible.”

The girl laughed again. Swann turned the machine back on, stepped away, then stepped back. “Want to try?”

The girl shook her head. Shy now. “I don’t think I’d be any good at it.”

“Sure you would. Of course you would. There’s really nothing to it. If I can do it, you can do it.”

“You think?”

“Absolutely. And I’ll tell you what.”

“What?”

“Whatever you find you can keep.”

Her eyes lit up. It was like the best offer she’d ever had. “For real?” Swann gave her a brief demonstration. She took the detector from him.

“Try near the entrance to the path,” he said, pointing to the asphalt-paved lane leading into the forest of trees. “A lot of times people will pull things out of their pockets right there—sweatbands, sunglasses, mosquito spray—and things can fly out and get lost in the leaves. It can be a real gold mine.”

“Okay. I don’t know. I’m not really… okay.” The girl began to scan where he told her to look. She waved the machine back and forth, back and forth, like a divining rod, settling the weight.

“A little slower,” he said.

“Okay.”

Left, left, left, Swann thought. Stop.

“Right around here?”

“Yes.”

More to the left. Stop. Right. Stop.

The machine beeped.

Yes.

“Hey! I think I found something! Does this mean I found something?” she asked.

“It does indeed.”

“What do I do?”

“I’ll show you.”

SHE MODELED the bangle. “So this is really mine?”

“Finders, keepers.”

The paste jewelry sparkled in the sun. To the girl, it was a Tiffany tennis bracelet.

He glanced at his watch. “Well, I’ve got to get back to work. They only let me do this on my break. It was nice to meet you, Claire.” He pointed to the bracelet. “Very cool find, by the way. I think you’re a natural sleuth.”

He put the detector over one shoulder, and began to walk away.

“ ’Scuse me.”

Joseph Swann stopped, turned. “Yes?”

“I was wondering something.”

“Okay.”

“Is there, I mean, do you guys have, like, campgrounds around here?”

“Campgrounds? Sure,” he said. “About a mile up this way. Nice, too.”

“I’m not with…” she trailed off, pointing back over her shoulder. She meant she was not with anybody. She meant she was alone. He knew this already.

“Don’t worry,” Swann said. “It’s okay. I’ll tell them you’re my cousin or something. You won’t even need ID. I’ve got a little juice around here. It’s a really nice place. Safe, too.”

“Cool.”

Claire Finneran smiled. Joseph Swann smiled back.

“It’s right up here,” he said. “C’mon. I’ll show you.”

No hesitation now. She grabbed her bag.

They walked into the woods.

THIRTY-SIX

BYRNE SAT IN THE CAR, watching. The man stood across the vacant lot, leaning against a half-demolished brick wall. The man had been there every day at the same time for the past three days, probably long before that. He wore the same clothes. He wore the same hat, the same expression. To Byrne he looked emptied, as if someone had scooped out everything that made him human and left just the shell, a brittle shell at that.

This had become Robert O’Riordan’s vigil, the same as a deathwatch, even though his daughter had already died. Or perhaps she had not, in his mind. Perhaps he expected her to appear in one of the windows, like some spectral Juliet. Or maybe his desires were more earthbound, and practical. Maybe he expected Caitlin’s killer to return to the scene of the crime, as killers were wont to do.

What would he then do? Byrne wondered. Was he armed? Did Caitlin’s father have the nerve to pull the trigger or launch the blade, based on a suspicion?

Byrne had talked to hundreds of fathers in his time on the job, men who had lost a son or daughter to violence. Each faced the darkness in his own way.

Byrne glanced at the man. There was no reaching him. Not now.

He started the car. But before he could pull out into traffic his phone rang. It was Jessica.

“We’ve got something,” she said. “Meet me at the lab.”

THIRTY-SEVEN

TRACY MCGOVERN WAS Deputy Director of the Crime Lab. A tall, slender woman of fifty, she had silver, shoulder-length hair, blunt-cut bangs. She favored shapeless black suits, rock-and-roll T-shirts, and Ecco walkers. Tracy had spent nearly ten years working with the FBI’s Mitochondrial DNA Unit—a division that examines items of evidence associated with cold cases, as well as small pieces of evidence containing little biological material—before returning to her hometown of Philadelphia. According to her colleagues, she had the unique ability to sleep three twenty-minute stretches per twenty-four-hour period, right at her desk, and continue working on a case until the perpetrator was caught. Tracy McGovern was not so much a bloodhound as she was a greyhound.

THE THREE BOXES from the Shiloh Street crime scene were on the floor. In the harsh light of the lab they looked even brighter, more colorful. It was hard to reconcile this with the purpose for which they had been used.

“There were no prints on the boxes,” Tracy said. “They’ve been rather thoroughly wiped down with a common household cleaning solution.”

Byrne again noted the craftsmanship that went into the design and construction of these boxes. The mitered edges were almost invisible.

“These hinges look expensive,” Byrne said.

“They are,” Tracy said. “They’re made by an Austrian company called Grass. They’re available from only a few dozen companies on the Internet. You might want to check them out.” Tracy handed Byrne a printout of specialty hardware websites.