Veteran Tim O'Brien writes novels about it. Even in those ostensibly not about the war - and In the Lake of the Woods is not - he is still writing a Vietnam novel. In The Lake of the Woods is about failure, about falling from great heights; something America knows well enough.

John Wade is a failure. He strove for the greatest heights of political office - the Senate, the White House - and was beaten by his own past. With his wife Kathy, he retreats to a cabin by a lake near the Canadian border, stuffs the telephone under the kitchen sink and retires into numb self-pity.

Then Kathy vanishes.

She's there and the next morning not. Gone too their boat. A search is belatedly mounted but neither Kathy nor the boat are ever seen again. There is mystery and mystery that remains. O'Brien makes it plain that there is no solution, no pat explanation. Life, he seems to say, does not mirror art. The last page does not always have all the answers.

O'Brien's methods are at once intricate and remarkably lucid. Into the central narrative he injects flashbacks to Wade's political manoeuvrings, to college courtship, and most tellingly to Vietnam. As a child Wade was a junior magician, and O'Brien cleverly weaves throughout his story the man's sleight of hand in South East Asia (where the men called him Sorcerer) to make whole villages disappear in firestorms, his own part in the massacre at My Lai vanish, and now the final trick - the one he no longer understands - of conjuring his own wife's disappearance.

Further to that - and at great risk - the author loads the book with chapters of Evidence - quotes from those involved in the search, trial testimony from My Lai - and Hypothesis - positing a string of possible accounts for Kathy's disappearance, from accident to flight to Wade's brutal, despairing murder. Both work remarkably well, and it's only toward the end, where O'Brien senses the difficulty of ending a book with no end, he lards the technique (extensive footnotes litter these pages) in search of profundity and narrowly avoids toppling the whole novel. There the book is lost, floundering in the lake itself. Where it works best is, inevitably, back in Vietnam where he coldly, clinically recites a litany of calm atrocities, allowing men to rape and mutilate and slaughter whole villages as a job of work.

There is completeness, a sense of debits being paid that precludes the need of O'Brien's attempts at redemption. The book's very irresolution is its strength - the perpetual openendedness the war has bequeathed to America - and one is left feeling cheated by the last thirty odd pages, as though O'Brien hasn't quite the courage of his convictions. In the Lake of the Woods is a deft, provocative novel that at the final hurdle seems content to exchange that for compromise.