On a sunny Sunday last July, Clark Rockefeller left his stately accommodations in Boston’s venerable Algonquin Club, the gentlemen’s establishment founded in 1886. Dressed in khakis and a blue Lacoste shirt, he was carrying his seven-year-old daughter, Reigh Storrow Mills Boss, whom he called Snooks, on his shoulders, walking toward Boston Common, where they were going to ride the swan boats in the Public Garden.

“Good morning, Mr. Rockefeller,” people greeted him, for he was well known in this Beacon Hill neighborhood. He had lived here for a year and a half in a $2.7 million, four-story, ivy-covered town house on one of the best streets. But that was before his wife, Sandra, left him and dragged him through a humiliating divorce, taking not only the Boston house but also their second home, in New Hampshire. In addition, she won custody of their daughter, moving her to London with her, and restricting him to three eight-hour visits a year, in the company of a social worker, who was tagging along that morning like a third wheel.

Nevertheless, he was still Clark Rockefeller. At 47, he still had his name, his intelligence, an extraordinary art collection, close friends in high places, and his memberships in clubs up and down the Eastern Seaboard, where he could sleep and take his meals, having long ago decided that hotels and restaurants were for the bourgeoisie. He also had a divorce settlement of $800,000, at least $300,000 of which he had converted into Krugerrands and then into gold U.S. coins, keeping the rest in cash. And now he had his beloved daughter with him again, for a blissful day together.

As they approached Marlborough Street, a tree-lined avenue on which Edward Kennedy has a house, a black S.U.V. limousine cruised to the curb. Rockefeller had told the driver that he and Snooks had a lunch date in Newport, Rhode Island, with a senator’s son, and that he might need help getting rid of a clingy friend (the court-appointed social worker...