"I… I'm not sure."

"I've just been meeting with Lincoln Rhyme's physician."

"Yes?"

"I've got to talk to you about something."

Her cell phone rang and Sachs jumped at the sound. As she reached for the phone she realized that Sung's hand was still resting on her arm.

Sung eased back into the booth bench and she answered, "Hello?"

"Officer, where the hell are you?" It was Lon Sellitto.

She was reluctant to say but she glanced at the patrol car across the street and had a feeling that they might have told the detective where she was. She said, "With that witness, John Sung."

"Why?"

"Just needed to follow up on a few things."

Not a lie, she thought. Not exactly.

"Well, finish following up," the man said gruffly. "We need you here, at Rhyme's. There's evidence to look at."

Jesus, she thought. What's eating him?

"I'll be right there."

"Make sure you are," the detective snapped.

Perplexed at his attitude, she disconnected the line and said to Sung, "I have to go."

A hopeful expression on his face, the doctor asked, "Have you found Sam Chang and the others from the ship?"

"Not yet."

As she rose he startled her by asking quickly, "I'd be honored if you would come back to see me. I could continue my treatment." Sung pushed the bag of herbs and pills toward her.

She hesitated only a moment before saying, "Sure. I'd like that."

"Hope we didn't interrupt anything important, Officer," Lon Sellitto said gruffly when she walked into Rhyme's living room.

She began to ask the detective what he meant but the criminalist himself began sniffing the air. Sachs responded with a querying glance.

"Recall my book, Sachs? 'Perfumes should not be worn by crime scene personnel because -'"

"'- odors not native to the scene may help identify individuals who have been present there.'"

"Good."

"But it's not perfume, Rhyme."

"Incense maybe?" he suggested.

"I met John Sung at a restaurant in his building. There was some incense burning."

"It stinks," Rhyme concluded.

"No, no," Sonny Li said. "Peaceful. Very peaceful."

No, it stank, petulant Rhyme thought. He glanced at the bag she carried and wrinkled his nose. "And what is that?"

"Medicine. For my arthritis."

"That stinks even more than the incense. What do you do with it?"

"Make it into tea."

"Probably tastes so vile that you forget about the pain in your joints.

Hope you enjoy it. I'll stick to scotch." He examined her closely for a moment. "Enjoy your visit with Dr. Sung, Sachs?"

"I -" she began uneasily, troubled by his edgy tone.

"How's he doing?" Rhyme asked blithely.

"Better," she answered.

"Talk much about his home in China? Where he travels? Whom he spends time with?"

"What're you getting at?" she asked cautiously.

"I'm just curious if what occurred to me occurred to you?"

"And that would be?"

"That Sung was the Ghost's bangshou. His assistant. His co-conspirator."

"What?" she gasped.

"Apparently it didn't," Rhyme observed.

"But there's no way. I've spent some time talking to him. He can't have any connection with the Ghost. I mean -"

"As a matter of fact," Rhyme interrupted, "he doesn't. We just got a report from the FBI office in Singapore. The Ghost's bangshou on the Dragon was Victor Au. The prints and picture match one of the three bodies the Coast Guard found this morning at the site of the sinking." He nodded toward the computer.

Sachs looked at the picture on Rhyme's screen and then glanced at the whiteboard on which were taped the Coast Guard's pictures of the bodies. Au was the one who'd drowned, not been shot.

Rhyme said sternly, "Sung's clean. But we didn't know that until ten minutes ago. I told you to be careful, Sachs. And you just dropped by Sung's to socialize. Don't go getting careless on me." His voice rose, saying, "And that goes for everybody!"

Search well but watch your back…

"Sorry," she muttered.

What was distracting her? Rhyme wondered again. But he said only, "Back to work, boys and girls." Then nodded at the electrostatic shoe-prints from the Tang crime scene that Thom had mounted on the evidence board. There was not much they could tell except that the Ghost's shoeprints, though an average size shoe, about an 8 in America, were larger than the three prints of his accomplices.

"Now, what about the trace that was in the Ghost's shoes, Mel?"

"Okay, Lincoln," the tech said slowly, looking over the screen of the chromatograph. "We've got something here. Very old oxidized iron flakes, old wood fibers and ash and silicon – looks like glass dust. And then the main act is a dark, low-luster mineral in large concentrations – montmorillonite. Alkaline oxide too."

Okay, Rhyme mused. Where the hell did it come from? He nodded slowly then closed his eyes and began, figuratively, to pace.

When he'd been head of IRD – the Investigation and Resources Division of the NYPD, the forensic unit – Rhyme had walked everywhere in New York City. He carried small bags and jars in his pockets for the samples of soil and concrete and dust and vegetation he'd collect to add to his knowledge of the city. A criminalist must know his territory in a thousand different ways: as sociologist, cartographer, geologist, engineer, botanist, zoologist, historian.

He realized that there was something familiar about the trace that Cooper was describing. But what?

Wait, there's a thought. Hold on to it.

Damn, it slipped away.

"Hey, Loaban?" a voice called, but from a distance. Rhyme ignored Li and continued to walk intently through, then fly over, the various neighborhoods of the city.

"Is he -?"

"Shhhhh," Sachs said firmly.

Freeing him to continue on his journey.

He sailed over the Columbia University tower, over Central Park with its loam and limestone and wildlife excrement, through the streets of Midtown coated with the residue of the tons of soot that fall upon them daily, the boat basins with their peculiar mix of gasoline, propane and diesel fuel, the decaying parts of the Bronx with their lead paint and old plaster mixed with sawdust as filler…

Soaring, soaring…

Until he came to one place.

His eyes opened.

"Downtown," he said. "The Ghost's downtown."

"Sure." Alan Coe shrugged. " Chinatown."

"No, not Chinatown," Rhyme replied. "Battery Park City or one of the developments around there."

"How'd you figure that out?" Sellitto asked.

"That montmorillonite? It's bentonite. That's a clay used as slurry to keep groundwater out of foundations when construction crews dig deep foundations. When they built the World Trade Center they sunk the foundation sixty-five feet down to the bedrock. The builder used millions of tons of bentonite. It's all over the place down there."

"But they use bentonite in a lot of places," Cooper pointed out.

"Sure, but the other trace materials Sachs found are from there too. That whole area is landfill and it's full of rusted metal and glass trace. And the ash? To clear the old piers down there the builders burned them."

"And it's only twenty minutes from Chinatown," Deng pointed out.

Thom wrote this on the evidence chart.

Still, it was a huge area and contained many high-density buildings: hotels, apartments and office buildings. They would need more information in order to narrow down exactly where the Ghost might be staying.

Sonny Li was pacing, walking in front of the board.

"Hey, Loaban, I got some ideas too."

"About what?" Rhyme grumbled. The man reeked of cigarette smoke. Rhyme had never smoked but he felt a huge burst of crip envy – that this man could partake in his vices all by himself, without having to track down a conspirator to help him.