The detective asked to see her ID again and she showed it to him. "Norma Sedgwick."

  "Hold on a minute."

  He said to Norma. "Just have to check."

  She didn't seem mad but her face registered a bit of "whatever." It seemed like a rookie putdown. Okay, you feddie bitch, you ever get shot at by a crank-crazed eighteen-year-old armed with a SIG-Sauer and a knife? Which is how he'd spent last Monday evening.

  He just smiled at her.

  On the other end of the line Sellitto's hand was over the receiver and he was talking with someone else. The detective wondered if it was the legendary Lincoln Rhyme. He knew Sellitto worked with him from time to time. He'd never met Rhyme. There were rumors that he didn't really exist.

  A few minutes later--it seemed like forever--Sellitto came back on the line.

  "Yeah, it's okay."

  Thank you, the detective thought. He could leave Mrs. Larkin and her grief and flee back to the place where he was a lot more comfortable: the drug world of East New York and the South Bronx.

  "Norma, where're we going?" Kitty, in the backseat, asked the stocky, attractive State Department agent, driving the Lincoln Town Car.

  "A hotel near our office in Midtown. We basically own one of the upper floors, so the staff doesn't put any guests there without our okay. Right now it's empty. You'll be the only one there. I'll be staying in the room across the hall, and another agent'll be there through the night. It's not the best hotel in the world, probably not what you're used to, but not bad. In any case, it's safer than you staying in your town house."

  "Maybe," the widow said softly. "But I'm going back there as soon as I can." She looked up and, in the rearview mirror, saw the agent's dark face studying her. "Let's hope everything's resolved soon."

  They drove in silence for a few minutes. Then Norma asked, "How's your arm?"

  "It's nothing, really." The widow touched the bandage. Her wound still stung badly but she'd stopped taking the painkillers the doctor had prescribed for her.

  "Why is the State Department interested in me? I don't quite understand."

  "Well, your husband's work overseas."

  "What do you mean?"

  "Sensitive issues. You know." She didn't add anything more.

  And Kitty thought: This is ridiculous. The last thing in the world she wanted was a bodyguard. She'd try to have the woman sent back to her office as soon as Peter Larkin and his wife arrived.

  Kitty was thinking of Peter and his family when she became aware that Norma Sedgwick had stiffened. Her shoulders hunched and she kept glancing into the rearview mirror. "Mrs. Larkin, I think there's a vehicle following us."

  "What?" Kitty turned around. "Impossible."

  "No, I'm pretty sure. I've been practicing evasive turns but he's stayed with me the whole time."

  "That green Jeep?"

  "That's it, yes."

  "Who's driving?"

  "A man, I think. White. Seems to be alone."

  Kitty looked. Couldn't see inside. The windows were tinted.

  Norma picked up her cell phone and started to make a call.

  This was crazy, Kitty thought. It made no sense for--

  "Look out!" Norma cried.

  In a burst of speed the Cherokee accelerated right toward them and then drove them off the street over the curb into the park.

  "What's he doing?" Norma barked.

  "I can't tell!"

  Into her phone the agent said, "This is Sedgwick. We've got an assailant! Madison and Twenty-third. The park. He's--"

  The Jeep then backed up and accelerated directly toward them.

  Kitty screamed, lowered her head and waited for the impact.

  But Norma accelerated and drove the car farther onto the grass of the park, stopping just before slamming into a temporary chain-link fence around a construction site. The Jeep bounded over the curb and came to a stop nearby.

  "Get out, get the hell out!" Norma shouted. "Move!" She jumped from the front seat and, gun in her hand, ripped the back door open.

  Clutching her purse, Kitty scrabbled out of the car. Norma took her by the arm and virtually dragged her into a stand of bushes, while pedestrians and park sitters fled. The Jeep stopped. The door flew open and Kitty believed the driver slid out.

  "Are you all right?" Holding her weapon, Norma looked her over carefully.

  "Yes, yes!" Kitty shouted. "I'm fine. Watch him! He's out of the car."

  The attacker, a solid white man in a dark suit and white shirt, moved quickly through the bushes toward them, then vanished behind a pile of construction material.

  "Where is he? Where?"

  Kitty glanced down at the gun in the woman's hand. She held it steady and seemed to know what she was doing. But she'd driven them into a cul de sac. There was nowhere to run. Kitty looked back toward the car. Nothing.

  Motion above them.

  Norma barked a scream, and Kitty looked up to see a figure hanging over the fence, a gun in his hand.

  But it wasn't the attacker. They were looking at a uniformed NYPD officer. He saw the ID around Norma's neck but he wasn't taking chances. His gun was aimed directly toward the agent.

  "Lower the weapon and identify yourself!"

  "I'm State Department. Security."

  "Lower the weapon and show me."

  "Jesus Christ," Kitty snapped. "She's guarding me. There's a man after us."

  Norma pointed her gun toward the ground and with her other hand held out her ID. He read it and nodded. "You should've called it in."

  "It just happened. Look, over there. Your two o'clock. White male, big guy. Drove us off the street. Probably armed."

  "What's he after?"

  "She's a homicide witness."

  Then the officer frowned. "Is that him?" He was gazing at Norma's car. Kitty saw a man crouching behind it.

  "Yeah," Norma said. Then to Kitty, "Get down!" And shoved her onto the asphalt walkway they were crouching on. Kitty was furious. She should've insisted they stay at the town house.

  "You, wait!" the officer called, starting forward. "Police. Don't move!"

  But by then the attacker had realized that he was outnumbered. He raced back to his Jeep. He backed the vehicle over the curb and sped up Madison, leaving a trail of blue smoke in his wake.

  Via the high-def video system, Lincoln Rhyme, in his lab, was watching Kitty Larkin talk to Sellitto and Sachs inside the black Town Car. The widow was giving them an account of the incident in a shaky voice.

  Rhyme was thinking: This system is quite an invention. It was as if the people were right there in front of him.

  "I couldn't really say what happened," Kitty said. "It was all so fast. I didn't even see him clearly."

  Norma Sedgwick gave a similar account of the incident. They differed in the color of the Jeep's shade of green, in the height of the assailant, in the color of his shirt.

  Witnesses . . . Rhyme didn't have much faith in them. Even honest ones get confused. They miss things. They misinterpret what they do see.

  He was impatient. "Sachs?"

  He saw the screen jump a little as she heard his voice.

  "Excuse me," she said to Kitty and Sellitto. The scene swiveled as she climbed out of the car and walked away.

  "What, Rhyme?"

  "We don't need to worry about what they saw or didn't see. I want the scene searched. Every inch."

  "Okay, Rhyme. I'll get to work."

  Sachs walked the grid--Rhyme's term for the most comprehensive, some would say compulsive, way of searching a crime scene--with her usual diligence. A lab tech from Queens processed the evidence in the back of the Crime Scene's rapid response vehicle. But the only things relating to the Larkin killing were two more of the coir fibers like the one on the balcony. One of the fibers was pressed into a small black fleck, which might've come from an old leather-bound book; Rhyme remembered similar evidence from a case some years ago.

  "Nothing else?" he asked, irritated.

&nbs
p; "Nope."

  Rhyme sighed.

  There is a well-known rule in forensics called Locard's Principle. The Frenchman Edmond Locard, one of the fathers of forensic science, came up with a rule that posited an inevitable exchange of trace evidence (he spoke of "dust") between the perpetrator and either the crime scene or the victim.

  Rhyme believed in Locard's Principle; in fact, it was the underlying force that drove him to relentlessly push those who worked for him--and to push himself too. If that connection, however fragile, can be established, then the perp might be found, crimes solved and future tragedies prevented.

  But making that link assumes the investigator can locate, identify and grasp the implications of that trace evidence. In the case of the Larkin homicide Rhyme wasn't sure that he could. Circumstance might play a role in this--the environment, third parties, fate. Then too the killer might simply be too smart and diligent. Too pro-fessional, as Fred Dellray had observed.

  Sachs took every defeat personally. "Sorry, Rhyme. I know it's important."

  He said something dismissive. Not to worry, we'll keep looking over things in the lab here, maybe the autopsy will reveal something helpful . . . .

  But he supposed his reassurance rang false to her.

  It certainly did to him.

  "Are you all right?" Norma asked.

  "Knees hurt. When I went down on the ground."

  "Sorry about that," the agent said, looking over Kitty from the rearview mirror. Norma had high cheekbones and exotic Egyptian eyes.

  "Don't be silly. You saved my life." Kitty, though, was still angry. She lapsed into silence.

  They drove for another twenty minutes. Kitty realized they were going in circles a lot and doubling back. She looked behind her once and saw that they were being followed--only this time it was an unmarked police car driven by that tall officer with hair as red as her own, Amelia Sachs.

  Norma's phone rang. She picked it up, had a conversation and then disconnected.

  "That was her, the policewoman behind us. No sign of the Jeep."

  Kitty nodded. "And nobody saw the license plate?"

  "No. But they're probably stolen tags."

  They continued on, driving in a random pattern. Sachs would disappear occasionally, driving up one street and down another, apparently looking for the man's Jeep.

  The agent began, "I guess--"

  Her phone rang. "Agent Sedgwick . . . What?"

  Kitty looked in the mirror, alarmed. What now? She was getting sick of the intrigue.

  "It's Amelia," Norma said to her. "She said she spotted the Jeep! He's nearby."

  "Where?"

  "A block! He was driving parallel to us. How? There's no way he could've followed us!"

  She listened into the phone again. Then reported to Kitty, "She's in pursuit. She's called in some other units. He's headed toward the FDR." Into the phone she asked, "How did he find us? . . . You think? Hold on."

  Norma asked Kitty, "He was hiding behind our car in Madison Square Park, right?"

  "Yes."

  She relayed this to the policewoman. There was a pause. "Okay, maybe. We'll check."

  Norma disconnected. "She thinks he might not've been trying to hurt you back in the park. He wanted to get us out of the car to plant a tracker after we jumped out."

  "A tracker?"

  "Like a GPS, a homing device. I'm going to look." She parked and climbed out, saying, "You check the backseat. And your suitcases. He might've slipped it in there. It would be a small plastic or metal box."

  Lord, what a nightmare this was, Kitty thought, even angrier now. Who the hell was this guy? Who'd hired him?

  Kitty tore open her two suitcases and dumped the contents on the seat, looking through everything carefully.

  Nothing.

  But then she heard: "Hey, check it out."

  Kitty looked out the window and saw the State Department agent holding a small white cylinder about three inches across, resting on a tissue so she wouldn't disturb fingerprints, Kitty guessed. "Magnetized, stuck up in the wheel well. It's a big one. Probably has a range of five miles. He could've found us anywhere in the area. Damn, that was a good call." She set it on the street near the curb, hunched down and, using the tissue, tinkered, apparently disabling it.

  A moment later Norma's phone rang again. The agent listened and then reported in a grim voice, "He got away. Disappeared on the Lower East Side."

  Kitty rubbed her face, disgusted.

  Norma told the detective about the tracking device and added that they were going on to the hotel.

  "Wait," said Kitty as she repacked the suitcases. "Why do you think he only left one tracker?"

  The agent blinked. Then nodded. She said into the phone, "Detective Sachs, you think you could give us a ride?"

  Fifteen minutes later Amelia Sachs arrived. Norma handed her the tracker and she put it in a plastic bag.

  Then the agent hustled Kitty Larkin into the detective's car and together the three women drove to the hotel. On the way the agent arranged for another State Department security person to pick up the Town Car and get it back to the pool for a complete inspection. There was even some speculation that the killer might've planted an explosive device at the same time he stuck the tracker in the wheel well, so the NYPD bomb squad would have a look as well.

  Sachs dropped the women off, explaining that she'd take the tracker back to the town house of that officer in the wheelchair, or consultant, whatever he was, Lincoln Rhyme. She sped off.

  Norma escorted Kitty inside the hotel. It was a pretty seedy place, the woman thought. She would have expected material witnesses and security-conscious diplomats to be housed in better digs.

  The agent spoke to someone at the front desk, handed him an envelope and returned to Kitty.

  "Do I need to check in?"

  "No, everything's taken care of."

  They got out on the fourteenth floor. Norma showed her to a room, checked it out herself and handed her the key. "You can call room service for anything you want."

  "I just want to call my family and Peter and then get some rest."

  "Sure, dear, you go right ahead. I'll be across the hall if you need anything."

  Kitty hung the Do Not Disturb sign on the knob and stepped into the room. It was just as tacky as the lobby suggested and smelled of mildew. She sat heavily on the bed, sighing. She noticed the window shades were up, which seemed a stupid idea for a hotel where they stashed witnesses. She rose and pulled the drapes shut, then turned the lights on in the room.

  She called the number of Peter Larkin's office and identified herself. She accepted the gush of sympathy the man's secretary offered and then asked when Peter and his wife would be arriving. It would be around nine that night. She left a message for him to call her as soon as they got in.

  Then she kicked her shoes off, lay back on the bed, closed her eyes and fell into a troubled sleep.

  Rhyme pressed his head back into the headrest of his wheelchair. He felt Sachs's hand curl around his neck and massage. He could feel her hand at one moment and then, though he knew she continued the massage, the sensation vanished as her fingers moved down, below the fourth cervical vertebra, the site of his disabling injury.

  At another time, this might give rise to reflections--either on his condition, or on his relationship with Amelia Sachs. But now he was aware of nothing but the urgency to nail the killer of Ron Larkin, the man who gave away billions.

  "How're we doing, Mel?"

  "Give me a minute."

  "You've had plenty of them. What's going on?"

  The massaging sensation stopped, but this was due not to the migration of her hand but because she'd stepped away and was helping Cooper prepare a slide for examination under the microscope.

  Rhyme looked over the updated evidence chart for the hundredth time.

  The answer was there. It had to be. There were no other options. No witnesses, no clear motives, no succinct list of suspects.

&
nbsp; The evidence, the minuscule bits of trace, held the key.

  Locard's Principle . . .

  Rhyme glanced at the clock.

  "Mel?"

  Without looking up from the Bausch and Lomb, the tech repeated patiently, "It should only be a minute."

  But every minute that passed meant that the killer was sixty seconds closer to escaping.

  Or, Rhyme feared, sixty seconds closer to murdering once again.

  Carter was sitting in his green Jeep, looking over Brooklyn from a spot near the South Street Seaport.

  He was sipping coffee and enjoying the view. The tall-masted clipper ship, the bridges, the boat traffic.

  Carter had no boss except the people who hired him, and he kept his own hours. Sometimes he'd get up early--four a.m.--and, when the Fulton Fish Market was still operating, drive here. He'd wander past stalls, staring at the tuna, the squid, the flounder, the crabs. It reminded him of seaports overseas.

  He was sorry the fish market had closed. Financial problems, he guessed. Or unions maybe.

  Carter had solved a lot of union problems in his day.

  His cell phone rang. He glanced down at caller ID.

  "Captain," he said in a respectful voice.

  He listened carefully, then said, "Sure. I can do that." He disconnected and placed a call overseas.

  Carter was glad he didn't have to go anywhere for a few minutes. A small cargo ship was steaming up the East River and he enjoyed watching its progress.

  "Oui?" a voice answered from the other side of the world.

  Carter began a conversation, not even aware that he'd lapsed into French.

  Kitty awoke to a phone call.

  She picked it up. "Hello?"

  Peter Larkin's voice said, "Kitty. How are you?"

  She'd seen plenty of pictures of him, but only met the man once, at the wedding. She remembered him clearly: tall, lean, with thinning hair. He resembled his brother only in facial structure.

  "Oh, Peter, this is so terrible."

  "Are you doing okay?"

  "I suppose." She cleared her throat. "I was just asleep, and I was dreaming about him. I woke up and for a minute I was fine. Then I remembered what had happened. It's so terrible. How are you?"

  "I can't even think. We didn't sleep on the plane . . . ."

  They commiserated for a few minutes more, then Peter explained they were at the airport and their luggage had just arrived. He and his wife would be in the town house in an hour or two. His daughter, a college student at Yale, was already there.