It must have sounded like a great idea. Take 50 years of Vietnam's history (which comes complete with all the violence and bloodshed any audience could want), add plenty of sex, sprinkle with oddities like self-castration, trading in slave labor and big-game hunting, blend in real people like Ho Chi Minh and Madame Nhu, invent four families whose members love, hate and torment each other through the generations, and easy as pie, visions of "Tai-Pan" or "Shogun" dance in the head.

Indeed, the payoff for Little, Brown and Anthony Grey from this novel, which is a Book-of-the-Month Club featured alternate and brought a six-figure paperback sale, may be rich, but most readers will feel left out of the deal.

"Saigon" stumbles on its long journey from copulation to death and back in prose so unremittingly awkward that it becomes an easy book to put down. Unless you like dialogue like this:

Wife to husband: "Did you make love with her?"

Husband to wife, after a lying denial: "Let's just forget all about it, shall we? . . . It's all in the past. We've got enough to worry about now with Pearl Harbor."

Or this between two brothers: "I thought we weren't out to shoot elephants or tigers."

"We're not going looking for them, genius--but they don't know that, do they? If they come looking for us with tusk and fang you'd better be ready with that Winchester peashooter of yours."

Or: "You've felt the mysterious power of the East set your blood frothing like champagne, haven't you?"

And the dialogue isn't the half of it: "She found herself searching back to her youth for reasons to explain the blind and selfish obsessions which had taken hold of her since they arrived in the French tropics and she wondered if her father's ruin and death by his own hand in the Louisiana cotton slump of '89, when she was only two years old, was the root cause."

"Saigon" begins in 1925 with a U.S. senator from Virginia, his wife and two sons visiting Vietnam to shoot big game for the senator's natural history museum. It ends in 1975 with the frantic exodus from Saigon of Americans and South Vietnamese as the communist forces swept into the city. And it doesn't miss a stop in between.

Grey makes sure that at least one character participates in all the major events of that half-century. One of the senator's sons, the only American character who survives the 789-page ordeal, is shot down over Vietnam during World War II and meets Ho Chi Minh. He later is on hand for the Vietnamese victory over the French after hopping in and out of Dienbienphu during that famous battle. All around him characters are dropping like flies, but he survives, and when the American involvement in Vietnam begins, one of his sons turns up as an Army officer, only to die by stepping on a mine during a vaguely Mylai-like massacre, and the other becomes a POW in North Vietnamese hands. A younger brother works for the CIA at the U.S. embassy in Saigon.

Naturally enough, the Tet Offensive finds our persistent American in Hue, where he is sheltered by the beautiful Vietcong he fathered . . . Well, I don't want to give away any more.

The action keeps coming relentlessly, without character development, without context, without just about anything to make it interesting. Some people reportedly used to have had the times of their lives shaking their heads over the Sears catalogue and muttering: "Whatever will they think of next. For some "Saigon" may provide the same pleasure.

Characters meet in the darnedest places. Sometimes coming together for love (and be warned that while no situation is handled gracefully in "Saigon," the writing about sex is particularly awful), but more often arriving in the same neighborhood so that one can be present as another is killed off.

It is all wildly improbable. Coincidence is followed by coincidence. Sections are introduced by flat historical notes, and the introduction of historical figures provides some of the book's oddest moments. It is one thing to have fictional characters lie flat on the page betraying no trace of flesh or blood, but yet another to have a cardboard Ho appear. And still another to have Ho ask the American protagonist to recite the Declaration of Independence slowly so that he can copy it down. But that isn't all. Minutes later, a messenger arrives with the news that Hiroshima has been bombed. What a day in the jungle! As the messenger puts it: "The Japs look like they're licked at last."

Now, a quiz. What do guns do? If you answered, "spit death," you understand how this novel is written. What do natives do? That's right, they "jabber."

It would have been more fun to report that this novel, by the former Reuters correspondent who was seized in Peking during the Cultural Revolution and held in solitary confinement for two years, belongs on the shelf of fat page-turners about the Orient. Vietnam is all the locale a novelist needs. Saigon, as character after character says, was a fascinating city, but "Saigon" is no way to learn about it. Or even to revisit it.