s he drove, the big detective fidgeted, he touched his belly, he tugged at his collar.

Kathryn Dance took in the body language of Lon Sellitto as he drove the unmarked Crown Vic — the same official vehicle she had in California — fast through the streets of New York, grille lights flashing, no siren.

The call she'd taken in the cab was from him, once again asking if she'd help them in the case. "I know you've got a flight, I know you've got to get home, but..."

He explained that they'd discovered a possible source for the clocks left at the Watchmaker's crime scenes and wanted her to interview the man who might've sold them. There was a possibility, though slight, that he had some connection with the Watchmaker and they wanted her opinion about him.

Dance had debated only a brief moment before agreeing. She'd regretted her abrupt departure from Lincoln Rhyme's town house earlier; Kathryn Dance hated leaving a case unfinished, even if it wasn't hers. She'd had the cab turn around and return to Rhyme's, where Lon Sellitto was waiting for her.

Now, in the detective's car, Dance asked, "It was your idea to call me, wasn't it?"

"How's that?" Sellitto asked.

"Not Lincoln's. He's not sure what to make of me."

His one-second pause was a flashing sign. Sellitto said, "You did a good job with that witness, Cobb."

Dance smiled. "I know I did. But he's not sure what to make of me."

Another pause. "He likes his evidence."

"Everybody has their weaknesses."

The detective laughed. He hit the siren button and they sped through a red light.

As he drove, Dance glanced at him, watched his hands and eyes, listened to his voice. She assessed: He's truly obsessed with getting the Watchmaker, and the other cases undoubtedly sitting on his desk now are as insubstantial as steam. And, as she'd observed when he was in her class yesterday, he was dogged and savvy, with no problem taking as much time as he needed to understand a problem or to get an interrogation technique right; if anybody grew impatient with him, well, that was their problem.

His energy's nervous but very different from that of Amelia Sachs, who has harm issues. He grumbles out of habit but he's essentially a very content man.

This was something Dance did automically, the analysis. A gesture, a glance, an offhand statement became to her another piece of that miraculous puzzle that was a human being. She was usually able to shut it off when she wished — it's no fun to be out for a Pinot Grigio or Anchor Steam beer and finding yourself analyzing your drinking buddies (and it's a lot less fun for them). But sometimes the thoughts just flowed; this habit went with the territory of being Kathryn Dance.

The people addict...

"You have a family?" he asked.

"Two children, yes."

"And what's your husband do?"

"I'm a widow." Dance's job was recognizing the effect of different tones of voice, and she now delivered these words in a particular way, both offhand and grave, which he would take to mean "I don't want to talk about it." A woman might grip her arm in sympathy; Sellitto did what most of his sex would: muttered a genuine but awkward "sorry" and moved on. He began talking about the evidence they'd found in the case and the leads — which were primarily nonleads. He was funny and gruff.

Ah, Bill... Know what? I think you'd've liked this guy. Dance knew that she did.

He told her about the store where it was likely the clocks came from. "I was saying, we don't think this Hallerstein's the doer. But that doesn't mean he's not involved. There's a chance this could get a little, you know, hairy."

"I'm not armed," Dance pointed out.

The laws about carrying guns from one jurisdiction to another are very strict and most cops are prohibited from bringing weapons from their home state to another. Not that it mattered; Dance had never fired her Glock except on the range and hoped to be able to say the same at her retirement party.

"I'll stay close," Sellitto reassured.

Hallerstein's Timepieces sat by itself in the middle of a gloomy block next to some wholesaler storefronts and warehouses. She eyed the place. The facade of the building was covered with scabby paint and grime but inside Hallerstein's shop window, protected by thick steel bars, the displayed clocks and watches were immaculate.

As they walked to the door Dance said, "If you don't mind, Detective, you establish the credentials, then let me handle things. That okay?"

Some cops, on their local turf, would've had a problem with her taking over. She'd sensed, though, that Sellitto would not (he had self-confidence to burn) but she needed to ask the question. He replied, "It's your, you know, ball game. That's why we called you."

"I'm going to say some things that sound a little odd. But it's part of the plan. Now, if I sense he's the perp, I'll lean forward and intertwine my fingers." A gesture that would make her more vulnerable and put the killer subconsciously at ease — less likely to go for a weapon. "If I think he's innocent, I'll take my purse off my shoulder and put it on the counter."

"Got it."

"Ready?"

"After you."

Dance pushed a button and they were buzzed into the shop. It was a small place, filled with every kind of clock imaginable: tall grandfather clocks, similar but smaller tabletop clocks, ornate sculptures containing timepieces, sleek, modern-style clocks, a hundred others, as well as fifty or sixty pristine watches.

They walked to the back, where a stocky man, balding, around sixty, was watching them cautiously from behind a counter. He was sitting in front of a dismantled clock mechanism that he was working on.

"Afternoon," Sellitto said.

The man nodded. "Hello."

"I'm Detective Sellitto with the police department and this is Agent Dance." Sellitto showed his ID. "You're Victor Hallerstein?"

"That's right." He pulled off a pair of glasses with an extra magnifying lens on a stalk at the side and glanced at Sellitto's badge. He smiled, with his mouth, though not his eyes, and he shook their hands.

"You're the owner?" Dance asked.

"Owner, right. Chief cook and bottle washer. I've had the store for ten years. Same location. Almost eleven."

Unnecessary information. Often a sign of deception. But it also could simply have been offered because he was uneasy at the unexpected appearance of two cops. One of the most important rules in kinesics is that a single gesture or behavior means very little. You can't accurately judge a response in isolation but only by looking at "clusters" — for instance, the body language of crossing one's arms has to be considered in light of the subject's eye contact, hand movement, tone of voice and the substance of what he's saying, as well as his choice of words.

And to be meaningful, the behavior has to be consistent when the same stimuli are repeated.

Kinesic analysis, Kathryn Dance would lecture, isn't about home runs; it's about a consistently well-played game.

"How can I help you? Police, huh? Another robbery around the neighborhood?"

Sellitto glanced at Dance, who didn't respond but gave a laugh and looked around. "I have never seen so many clocks in one place in my life."

"Been selling them for a long time."

"Are these all for sale?"

"Make me an offer I can't refuse." A laugh. Then: "Seriously, some I wouldn't sell. But most, sure. Hey, it's a store, right?"

"That one is beautiful."

He glanced at the one she was indicating. An Art Nouveau style in gold metal, with a simple face. "Seth Thomas, made in nineteen oh five. Stylish, dependable."

"Expensive?"

"Three hundred. It's only gold plate, mass produced... Now, you want expensive?" Hallerstein pointed to a ceramic clock, in pink, blue and purple, painted with flowers. Dance found it irritatingly gaudy. "Five times as much."

"Ah."

"I see that reaction. But in the clock collecting world, one man's tacky is another man's art." He smiled. The caution and concern weren't gone but Hallerstein was slightly less defensive.

She frowned. "At noon what do you do? Wear earplugs?"

A laugh. "Most of them, you can shut the chimes off. The cuckoos're the ones that drive me crazy. So to speak."

She asked a few more questions about his business, filing away a library of gestures and glances and tones and words — establishing the baseline for his behavior.

Finally, keeping her tone conversational, she asked, "Sir, we'd like to know: Did someone recently buy two clocks like this one?" She showed him the picture of one of the Arnold Products clocks left at the crime scenes. Her eyes scanned him as he stared at the photo, his face neutral. She decided he was studying it for too long, an indication that his mind was engaged in a debate.

"Can't say I recall. I sell a lot of clocks, believe me."

Faulty memory — a flag for the stress state of denial in a deceptive person, just like Ari Cobb earlier. His eyes scanned the photo again carefully, as if trying to be helpful, but his shoulder turned toward her slightly, his head dipped and his voice rose in pitch. "No, I really don't think so. Sorry, I can't help."

She sensed he was deceptive, not only from the kinesics but his recognition response (in his case, the neutral visage, which deviated from his expressive baseline); most likely he knew the clock. But was he deceptive because he simply didn't want to get involved, or because he sold clocks to someone he thought might be a criminal, or because he was involved in the killings himself?

Hands clasped in front of her, or purse on the counter?

In determining personality type, Dance had categorized the reluctant witness earlier, Cobb, as an extrovert; Hallerstein was the opposite, an introvert, someone who makes decisions based on intuition and emotion. She drew this conclusion about the dealer because of his clear passion for his clocks and the fact he was only a moderately successful businessman (he'd rather sell what he loved than run a mass-market operation and make more profit).

To get an introvert to tell the truth, she'd have to bond with him, make him feel comfortable. An attack like the one on Cobb would make Hallerstein freeze up instantly.

Dance sighed, her shoulders slumping. "You were our last hope." She sighed, glancing at Sellitto, who, bless him, gave a good portrayal of a disappointed cop, shaking his head with a grimace.

"Hope?" Hallerstein asked.

"The man who bought these clocks committed a very serious crime. They're the only real leads we have."

The concern that blossomed in Hallerstein's face seemed genuine but Kathryn Dance had met a lot of good actors. She put the paper back into her purse. "Those clocks were found next to his murder victims."

Eyes frozen for a moment. This is one stressed-out shopkeeper we've got ourselves here.

"Murder?"

"That's right. Two people were killed last night. The clocks might've been left as messages of some kind. We're not sure." Dance frowned. "The whole thing is pretty confusing. If I were going to murder someone and leave a message I wouldn't hide it thirty feet away from the victim. I'd leave it a lot closer and out in the open. So we just don't know."

Dance watched his reaction carefully. To her calculated misstatement, Hallerstein gave the same response as would anyone unfamiliar with the situation, a shake of the head at the tragedy but no other reaction. Had he been the killer, he would most likely have given a recognition response — usually centering around the eyes and nose — that her words didn't coincide with his knowledge of the facts. He would've thought: But the killer did leave it by the body; why would somebody move it? And that thought would have been accompanied by very specific gestures and body language.

A good deceiver can minimize a recognition response so that most people aren't aware of it but Dance's radar was operating at full strength and she believed the dealer passed the test. She was convinced he hadn't been at the crime scenes or knew the Watchmaker.

She put her purse on the counter.

Lon Sellitto moved his hand away from his hip, where it had been resting.

But her job had just begun. They'd established that the dealer wasn't the killer and didn't know him, but he definitely had information.

"Mr. Hallerstein, the people who were killed died in very unpleasant ways."

"Wait, they were on the news, right? A man was crushed? And then somebody was thrown into the river."

"Right."

"And... that clock was there?"

Almost "my" clock. But not quite.

Play the fish carefully, she told herself.

She nodded. "We think he's going to hurt somebody again. And like I said, you were our last hope. If we have to track down other dealers who might've sold the killer the clocks it could take weeks."

Hallerstein's face clouded.

Dismay is easily recognized in a person's face but it can arise in response to many different emotions — sympathy, pain, disappointment, sorrow, embarrassment — and only kinesics can reveal the source if the subject doesn't volunteer the information. Kathryn Dance now examined the man's eyes, his fingers caressing the clock in front of him, his tongue touching the corner of his lips. Suddenly she understood: Hallerstein was displaying the flight-or-fight response.

He was afraid — for his own safety.

Got it.

"Mr. Hallerstein, if you could remember anything to help us, we'd guarantee you were safe."

A glance at Sellitto, who nodded. "Oh, you bet. We'll put an officer outside your shop if we need to."

The unhappy man toyed with a tiny screwdriver.

Dance took the picture out of her purse again. "Could you just take another look? See if you can remember anything."

But he didn't need to look. His posture caved in slightly, chest receding, head forward. Hallerstein sprinted into the acceptance response state. "I'm sorry. I lied."

Which you hardly ever heard. She'd given him the chance to claim that he'd looked at the picture too fast or was confused. But he didn't care about that. Do not pass go — it was confession time, pure and simple.

"I knew the clock right away. The thing is, though, he said if I told anybody, he'd come back, he'd hurt me, he'd destroy all my watches and clocks, my whole collection! But I didn't know anything about any murder. I swear! I thought he was a crank." His jaw was trembling and he put his hand back on the casing of the clock he'd been working on. A gesture that Dance interpreted to mean he was desperately seeking comfort.

She sensed something else as well. Kinesic experts have to judge if the subject's responses are appropriate to the questions they've been asked or the facts they've been told. Hallerstein was troubled by the murders, yes, and afraid for himself and his treasures, but his reaction was out of proportion to what they'd been discussing.

She was about to explore this when the clock dealer explained exactly why he was so upset.

"He's leaving these clocks at the places where he kills his victims?" Hallerstein asked.

Sellitto nodded.

"Well, I have to tell you." His voice clutched and he continued in a whisper. "He didn't just buy two clocks. He bought ten."