Every once in a while a journalist happens upon an especially juicy story and somehow manages to squeeze every delicious drop out of it. This is just what Robert Harris has done in "Selling Hitler," the story of the manufacture and merchandising of the "Hitler diaries," the "most expensive and far-reaching fraud in publishing history," an undertaking that ultimately damaged a number of reputations and severely embarrassed three prominent publications. But the end of the story is widely known; what is not is the labyrinthine path by which that end was reached, and that is the story Robert Harris tells.

It's a humdinger. It brings in everything from intrigue to duplicity to self-delusion to greed -- greed, greed, above all greed -- and it involves a cast of characters ranging from the ploddingly ordinary to the impossibly bizarre. Its settings include the editorial offices of powerful publications, restaurants frequented by "adjutants, orderlies, chauffeurs and secretaries who had formed Hitler's inner circle," the yacht once owned by Hermann Goering, and the private museums presided over by collectors of Nazi memorabilia. It's loony tunes from first page to last, and Harris knows just how to play it: low-key, deadpan, wry.

The two central characters are Gerd Heidemann and Konrad Kujau. The former is the reporter for Stern, the German magazine, who discovered the "diaries" and eventually extracted some 9 million marks from Stern's bank account to purchase them -- many of which marks ended up in his own pocketbook. Harris portrays him as "restless, diffident, obsessive," hung up on Hitler to the extent that he went deeply into debt to purchase the Goering yacht -- on which he gave elaborate parties for former Nazis -- and eventually became "a man slowly sinking into a mire of obsession and fantasy about the Third Reich." He truly believed, until at last the evidence to the contrary became incontrovertible, that the "diaries" were real.

Kujau is the fellow who faked the diaries, a hard-core cynic and liar with a genius for forgery: "He slipped in and out of other people's handwriting as he did his various pseudonyms and biographies, with complete ease." He started by peddling his phony Nazi memorabilia to collectors, in particular a businessman named Fritz Stiefel, whose "gullibility was matched only by his willingness to spend money," but raised his sights when Heidemann learned of the existence of the "diaries" and began buying them for Stern.

What happened in the offices of that magazine -- as well as what eventually happened in the offices of Newsweek and The Sunday Times of London -- is an object lesson in the risks journalists can create for themselves when they desperately want to believe that a spectacular if improbable story is true. Though Heidemann's pleadings were initially rejected by Stern's editors, the magazine's managing director and others in the business offices ardently pursued the "diaries." Once they had them, they were so determined to cash in on this earth-shattering scoop that they refused to listen to those who questioned the documents' validity and subjected them only to "the bare minimum of authentication felt necessary to satisfy the rest of the world."

Even as Stern was going to press with its first story about the "diaries," it was presented with evidence seriously questioning their authenticity; yet it crashed along full speed ahead. The magazine's managers were in the grip of "two of the most ancient of human weaknesses -- vanity and greed." They believed absolutely in their own judgment, and they were desperate to cash in on a journalistic bonanza of unprecedented dimensions. Nothing, least of all scrupulous examination of the evidence, was about to hold them back.

The result was, for everyone involved, a calamity: For Heidemann and Kujau, who eventually went to jail; for Hugh Trevor-Roper, the historian, who hastily endorsed the "diaries" and then embarrassedly sought to cover his tracks; for many editors at Stern, The Sunday Times and Newsweek, who soon found themselves out of jobs or unable to advance beyond the ones they held; for collectors of Hitler memorabilia who discovered that they had paid large amounts of money for Hitler paintings and Nazi documents that were actually Kujau forgeries. But we are not dealing in tragedy here: They got what they deserved.

Among all these sharpies and weirdos, the weirdest by far is Heidemann. There's something rather poignant about his puppyish longing for approval, his pathetic faith in the "diaries," even his dotty fascination with dictators and Nazis. The scene that says it all occurs when he gives Trevor-Roper a tour of his private museum:

"At least two of the corridors were crammed with Nazi memorabilia. Then, turning the corner, came a section devoted to Mussolini. Finally, Heidemann conducted Trevor-Roper into an area with a few mementos of Idi Amin. 'Those,' he said, pointing to a pair of voluminous white cotton drawers, 'are Idi Amin's underpants.' "