Kathryn Dance became a cop.

The CBI doesn't break out kinesics as a specialty so Dance was technically just another investigative agent, working homicides, kidnappings, narcotics, terrorism and the like. Still, in law enforcement, talents are spotted early and news of her talent quickly spread. She found herself the resident expert in interview and interrogation (fine with her, since it gave her some bargaining power to trade off undercover and forensic work, which she had little interest in).

She now glanced at her watch, wondering how long this volunteer mission would take. Her flight wasn't until the afternoon but she'd have to give herself plenty of time to get to JFK; traffic in the city was horrendous, even worse than the 101 Freeway around San Jose. She couldn't miss the plane. She was eager to get back to her children, and-funny about caseloads-the files on your desk never seem to disappear when you're out of the office; they only multiply.

The cab squealed to a stop.

Dance squinted out the window. "Is this the right address?"

"It's the one you gave me."

"It doesn't look like a police station."

He glanced up at the ornate building. "Sure don't. That'll be six seventy-five."

Yes and no, Dance thought to herself.

It was a police station and yet it wasn't.

Lon Sellitto greeted her in the front hallway. The detective had taken her course in kinesics the day before at One Police Plaza and had just called, asking if she could come by now to give them a hand on a multiple homicide. When he'd telephoned he'd given her the address and she'd assumed it was a precinct house. It happened to be filled with nearly as much forensic equipment as the lab at the Monterey CBI headquarters but was, nonetheless, a private home.

And it was owned by Lincoln Rhyme, no less.

Another fact Sellitto had neglected to mention.

Dance had heard of Rhyme, of course-many law enforcers knew of the brilliant quadriplegic forensic detective-but wasn't aware of the details of his life or his role in the NYPD. The fact he was disabled soon failed to register; unless she was studying body language intentionally, Kathryn Dance tended to pay most attention to people's eyes. Besides, one of her colleagues in the CBI was a paraplegic and she was accustomed to people in wheelchairs.

Sellitto now introduced her to Rhyme and a tall, intense police detective named Amelia Sachs. Dance noted at once that they were more than professional partners. No great kinesic deductions were necessary to make this connection; when she walked in, Sachs had her fingers entwined with Rhyme's and was whispering something to him with a smile.

Sachs greeted her warmly and Sellitto introduced her to several other officers.

Dance was aware of a tinny sound coming from over her shoulder-ear-buds dangling behind her. She laughed and shut off her iPod, which she carried with her like a life-support system.

Sellitto and Sachs told her about the homicide case they needed some help on-a case that Rhyme seemed to be in charge of, though he was a civilian.

Rhyme didn't participate much in the discussion. His eyes continually returned to a large whiteboard, on which were notations of the evidence. The other officers were giving her details of the case, though she couldn't help but observe Rhyme-the way he squinted at the board, would mutter something under his breath and shake his head, as if chastising himself for missing something. Occasionally his eyes would close. Once or twice he offered a comment about the case but he largely ignored Dance.

She was amused. The agent was used to skepticism. Most often it arose because she simply didn't look like a typical cop, this five-foot-five woman with dark blond hair worn usually, as now, in a tight French braid, light purple lipstick, iPod earbuds dangling, the gold and abalone jewelry her mother had made, not to mention her passion-quirky shoes (chasing perps didn't usually figure in Dance's daily life as a cop).

Now, though, she suspected she understood Lincoln Rhyme's lack of interest. Like many forensic scientists, he wouldn't put much stock in kinesics and interviewing. He'd probably voted against calling her.

As for Dance herself, well, she recognized the value of physical evidence, but it had no appeal to her. It was the human side of crime and crime solving that made her own heart race.

Kinesics versus forensics…

Fair enough, Detective Rhyme.

While the handsome, sardonic and impatient criminalist continued to gaze at the evidence charts, Dance absorbed the details of the case, which was a strange one. The murders by the self-anointed Watchmaker were horrific, sure, but Dance wasn't shocked. She'd worked cases that were just as gruesome. And, after all, she lived in California, where Charles Manson had set the standard for evil.

Another detective from the NYPD, Dennis Baker, now told her specifically what they needed. They'd found a witness who might have some helpful information but he wasn't forthcoming with details.

"He claims he didn't see anything," Sachs added. "But I have a feeling he did."

Dance was disappointed that it wasn't a suspect but a witness she'd be interviewing. She preferred the challenge of confronting criminals, and the more deceitful the better. Still, interviewing witnesses took much less time than breaking suspects and she couldn't miss her flight.

"I'll see what I can do," she told them. She fished in her Coach purse and put on round glasses with pale pink frames.

Sachs gave her the details about Ari Cobb, the reluctant witness, laying out the chronology of the man's evening, as they'd been able to piece it together, and his behavior that morning.

Dance listened carefully as she sipped coffee that Rhyme's caregiver had poured for her and indulged in half a Danish.

When she'd gotten all the background Dance organized her thoughts. Then she said to them, "Okay, let me tell you what I've got in mind. First, a crash course. Lon heard this yesterday at the seminar but I'll let the rest of you know how I handle interviewing. Kinesics traditionally was studying somebody's physical behavior-body language-to understand their emotional state and whether they were being deceptive or not. Most people, including me, use the term now to mean all forms of communication-not just body language but spoken comments and written statements too.

"First, I'll take a baseline reading of the witness-see how he acts when he's answering things that we know are truthful-name, address, job, things like that. I'll note his gesturing, posture, word choice and the substance of what he says.

"Once I have the baseline I'll start asking questions and find out where he exhibits stress reactions. Which means he's either lying or has some important issues with the topic I'm asking him about. Up until then, what I've been doing is 'interviewing' him. Once I suspect he's lying, then the session will become an 'interrogation.' I start to whittle away at him, using a lot of different techniques, until we get to the truth."

"Perfect," said Baker. Although Rhyme was apparently in charge, Dennis Baker, Dance deduced, was from headquarters; he had the belabored look of a man on whose shoulders an investigation like this ultimately-and politically-rested.

"You have a map of the area we're talking about," Dance said. "I'd like to know the geography of the area involved. You can't be an effective interrogator without it. I like to say I need to know the subject's terrarium."

Lon Sellitto gave a fast laugh. Dance smiled in curiosity. He explained, "Lincoln says exactly the same about forensics. If you don't know the geography, you're working in a vacuum. Right, Linc?"

"Sorry?" the criminalist asked.

"Terrarium, you like that?"

"Ah." His polite smile was the equivalent of Dance's son saying, "Whatever."