By Vincent Bugliosi

With Bruce B. Henderson

Norton. 574 pp. $22.95

In 1974 two couples converged on an idyllic South Seas island, Palmyra, each seeking to escape civilization. Solidly middle-class, Mac and Muff Graham traveled on a well-appointed yacht. Living a more marginal existence, Buck Walker and Jennifer Jenkins were on the run, since Buck, an ex-con, had jumped bail on a drug-dealing charge. Their boat was a rickety affair. On Palmyra the two couples did not hit it off. Then Mac and Muff disappeared, and Buck and Jennifer arrived in Hawaii on Mac's boat -- Mac's repainted boat.

These are the bare bones of the first half of "And the Sea Will Tell." Vincent Bugliosi, prosecutor of Charles Manson and author of the best-selling "Helter Skelter," came by this book when Jennifer asked Bugliosi, now in private practice, to defend her against a murder charge when the body of Muff washed up on the island in a container six years later. Jennifer claimed Buck told her that Mac and Muff had drowned when their dinghy capsized, and that she, naively in love with Buck, believed him. After interviewing her and feeling reasonably convinced she was innocent, Bugliosi agreed to take her case (he had refused a similar plea from Jeffrey MacDonald, believing the former Green Beret officer -- subject of Joe McGinniss's "Fatal Vision" -- guilty of killing his wife and daughters).

Bugliosi's (and coauthor Bruce B. Henderson's) prose in the first half of the book ranges from serviceable to awful. The unfortunate opening paragraph alone sounds like an entry in the Bulwer-Lytton ("It was a dark and stormy night ...") bad-writing contest: "It had rained during the night, one of those warm tropical showers that leaves the air heavy and sweet. A steady breeze born far out at sea kissed the shore at sunrise, rustling the coconut palms. The clouds, like the folks around these parts in no hurry to move on, scattered slowly as the sun rose out of the ocean and washed the sky with bold streaks of light. A few arcs of rainbow loitered above, offering promise for the new day."

The authors indulge in more foreshadowing than a tarot reader: Jennifer "was struck ... with the thought that ... they should have heeded conventional wisdom. They should not have changed the boat's name. Bad luck will follow us wherever we go." A chapter later: "Alone in the car, Muff felt a chill that had nothing to do with the weather." Yet a few chapters later: " 'I'm ... not coming back,' Muff moaned {to a friend}.

" 'Oh, Muff, you can't -- '

" 'Mac and I -- we'll never see you again.' "

And still later, on the island: "Muff watched passively for a few minutes, then wandered alone up the path. She came across an enclave of old buildings that had been all but swallowed up by the jungle. Peeking into the crumbling shells of the structures, she had the strong feeling that strange, tragic things had happened on and around this island. Was it just her imagination?"

No; it's a lack of imagination on the writer's part as he struggles to implant a sense of impending doom in the reader.

In Part 2 Bugliosi appears as a character, and the narrative abruptly switches from the third person to, for him, the more comfortable first person. It is still wordy and top-heavy with legalistic detail, but his account of working out a defense strategy and of the unorthodox gambits he took is gripping. He had to distinguish in the minds of the jurors Jennifer from Buck, who had already in a separate trial been convicted of Muff's murder. He mounts an impressive case, painstakingly refuting almost every bit of circumstantial evidence arrayed against her.

But in the end he did not convince me of his client's innocence (though he convinced the jury). Rather, his arguments impressed me that Bugliosi knew how to put a better interpretive spin on the facts than did the prosecutor, Elliot Enoki. For instance, here he is explaining to the jury that Buck and Jennifer had no reason to steal Mac's boat since they weren't afraid of making a dangerous trip in their own boat to a neighboring island, despite the warnings of others: "Many people would never drive across town in cars that other people wouldn't think twice about traveling cross-country in."

This sounds good, but on inspection it doesn't hold water. If your car breaks down cross-country you can go to a garage. If your boat breaks down mid-ocean you're in, so to speak, over your head. I finished the book convinced that had Enoki defended Jennifer, and Bugliosi prosecuted her, she would, right now, be behind bars for the murder of Muff. For that matter, I felt -- chilling thought -- that had Bugliosi defended rather than prosecuted Manson, that maniac might right now be bouncing around the desert in a dune buggy. The reviewer's most recent book is the short-story collection "The Off-Season." He has written investigative crime articles for California magazine and the East Bay Express.