Dance came from a locale where the temperature was seventy-five, give or take, all year-round and you had to drive up Carmel Valley Road a long, long way to find enough sledding snow to keep your son and daughter happy. In her last-minute packing for the seminar here in New York, somehow she’d forgotten that the Northeast plus December equals the Himalayas.

She was reflecting: Here I can’t drop the last five pounds of what I gained in Mexico last month (where she’d done nothing but sit in a smoky room, interrogating a suspected kidnapper). If I can’t lose it, at least the extra weight ought to do its duty as insulation. Ain’t fair . . . She pulled her thin coat more tightly around her.

Kathryn Dance was a special agent with the California Bureau of Investigation, based in Monterey. She was one of the nation’s preeminent experts in interrogation and kinesics—the science of observing and analyzing the body language and verbal behavior of witnesses and suspects. She’d been in New York for the past three days presenting her kinesics seminar to local law enforcement agencies.

Kinesics is a rare specialty in police work, but to Kathryn Dance there was nothing like it. She was a people addict. They fascinated her, they electrified her. Confounded and challenged her too. These billions of odd creatures moving through the world, saying the strangest and most wonderful and terrible things . . . She felt what they felt, she feared what scared them, she got pleasure from their joy.

Dance had been a reporter after college: journalism, that profession tailor-made for the aimless with insatiable curiosities. She ended up on the crime beat and spent hours in courtrooms, observing lawyers and suspects and jurors. She realized something about herself: She could look at a witness, listen to his words and get an immediate sense of when he was telling the truth and when he wasn’t. She could look at jurors and see when they were bored or lost or angry or shocked, when they believed the suspect, when they didn’t. She could tell which lawyers were ill-suited to the bar and which were going to shine.

She could spot the cops whose whole heart was in their jobs and the ones who were only biding their time. (One of the former in particular caught her eye: a prematurely silver-haired FBI agent out of the San Jose field office, testifying with humor and panache in a gang trial she was covering. She finagled an exclusive interview with him after the guilty verdicts, and he finagled a date. Eight months later she and William Swenson were married.)

Eventually bored with the reporter’s life, Kathryn Dance decided on a career change. Life turned crazy for a time as she juggled her roles as mother of two small children and wife and grad student, but she managed to graduate from UC-Santa Cruz with a joint master’s in psych and communications. She opened a jury consulting business, advising attorneys which jurors to choose and which to avoid during voir dire jury selection. She was talented and made very good money. But six years ago, she decided to change course once again. With the help of a supportive, tireless husband and her mother and father, who lived in nearby Carmel, she headed back to school once more: the California State Bureau of Investigation training academy in Sacramento.