Life is going well for Ben Tyson. He has a good job, a beautiful wife with whom he has a terrific sex life, a 16-year-old son, a nice house in Garden City, Long Island, membership at the country club. Then one morning on the commuter train into Manhattan he notices a neighbor reading a book called "Hue: Death of a City." The man starts to look at Tyson funny, the way you might react if you found yourself sitting across from a mass-murderer on the 7:58.

It turns out the book contains the account of the massacre at Mise'ricorde Hospital during the Tet offensive in 1968. Tyson had been a lieutenant in charge of a platoon that didn't wait until coming home to start experiencing traumatic stress. His men were exhausted after weeks of nonstop combat. They approached the hospital. A white banner of surrender was hung out a window. Then two of Tyson's men were cut down by fire coming from the hospital. The French doctors arrogantly refused to treat Tyson's wounded, while continuing to operate on North Vietnamese army soldiers. Tyson's platoon went berserk, and in the ensuing carnage killed the wounded North Vietnamese, the doctors, the nurses, the nuns, the patients, everyone. White phosphorus grenades were tossed into the maternity ward, the hospital was put to the torch, a little amputee boy was shot escaping out a window. By the time it was over, a hundred people were dead, and now, 16 years later, two members of the platoon have broken the blood oath they took never to reveal what happened.

The book becomes a best seller, the world is outraged, the Army wants to court-martial Ben Tyson, and America gets to relive Vietnam all over again. The White House wishes it had never heard of him, and an agent of some Robert Ludlumesque government agency keeps appearing with offers of secret deals -- and threats.

Tyson's wife Marcy is a former antiwar madonna. She seems to have slept with half the antiwar movement, a fact to which the American Investigator (read: National Enquirer) devotes no small amount of coverage. All this is understandably upsetting to their 16-year-old son David, who under the circumstances might be expected to take up heroin, but he only calmly sips a beer in the kitchen as his father tells him that the troublesome book's description of the events at Mise'ricorde Hospital is, essentially, true. It is a good deal more complicated than that, and thereby hangs Tyson's extraordinary tale and DeMille's gripping novel.

The investigator dispatched by the Army to question Tyson is a young (and of course beautiful) woman named Karen Harper. She's bright -- everyone in "Word of Honor" is bright -- and the sexual tension between the two provides an interesting lubricity.

Vincent Corva, the lawyer Tyson hires, is "due for a miracle," having lost every court-martial case he's defended. He is in the tradition of the defender of the Caine mutineers: ethnic, unpredictable, cynical-but-compassionate and exciting to watch. (In what may be a nod to the book his own will be justifiably compared to, DeMille names one of the key figures in the Mise'ricorde Hospital massacre Cane.)

This is a powerful and resonant book, full of references to My Lai, the Dreyfus affair and even the Little Bighorn (Tyson's platoon is with the 7th Cavalry). The Army wants Tyson so it can make amends for the My Lai case. "No cover-ups, no legal blunders," says the shadowy agent who keeps popping up in steam baths, "no undue command influence, no congressional whining, no journalistic Monday-morning quarterbacking . . . Just justice. Even if we have to script it and fake it. Okay?" And as in the Dreyfus case, this one transcends the individual players. National honor is at stake.

And something else -- the truth. What really happened that day in Hue is revealed in a tantalizingly slow, suspenseful process. Oddly, the man most reluctant to spill the beans is the man who has everything to lose by not doing so: Tyson. He won't even tell his lawyer what happened until they're in court. If Tyson is going to break his oath, then he's going to make everyone work to find the truth. The truth, he says, is not easy. It must be hard won; only then can it make you free. Tyson's moral fineness, as well as DeMille's virtuosity as a storyteller, makes the conclusion as satisfying as it is dramatic.