It had to be destiny. John Kennedy had been linked to some of the most talked-about women in the world. He had jogged in Central Park with Madonna. He had gone deep-powder skiing in Telluride, Colo., with Daryl Hannah. But when The Sexiest Man Alive stepped into a New York charity event and first glimpsed Carolyn Bessette across the room, his glitzy world stopped spinning. In this willowy, quiet beauty with a cool, seductive style, Kennedy had finally met his match. "They had instant eye lock," says Paul Wilmot, a publicist and Bessette's former boss. "The minute they saw each other they were mad for one another. He called her the next day."

Carolyn Bessette stepped willingly into Camelot. They were devoted to each other, and in John Kennedy she found a partner who could escort her through the maze of New York's rarefied political circles while also appreciating the comforts of their younger, hipper neighborhood in downtown Manhattan. But she never developed his easy way of running the gauntlet of gawkers and paparazzi that hounded them everywhere. And in the end her own family found itself drawn into the kind of tragedy that has struck the Kennedys again and...