In 1970, McGraw-Hill announced it would publish a book written by the ultra-reclusive billionaire Howard Hughes in collaboration with Clifford Irving, a writer with only a single title to his credit and no discernable track record as a journalist.

With thousands of copies set to hit bookstores and an excerpt just about to appear in Life Magazine, Hughes refuted all claim to the book’s authenticity in a telephone press conference that was broadcast nationally in early 1971. “I only wish I were still in the movie business,” the disembodied voice of the former RKO Studios chief said at the time “because I don’t remember any script I ever saw in Hollywood as wild or imagination-stretching as this autobiography yarn has turned out to be.”

Lasse Hallström’s “The Hoax” is an alternatively breezy, brooding, farcical, and moralistic account of Irving’s failed attempt to pass off his fictionalized autobiography of Howard Hughes as the real thing.

Clifford Irving (Richard Gere), the film tells us, is a frustrated novelist, and the Hughes con job begins as a kind of elaborate silent protest against a publishing establishment that has failed to appreciate his talent. After editors cancel what is to be his debut novel and his agent warns him that he needs to come up with a suit-proof pitch, Irving forges a letter from the reclusive Hughes, authorizing him to co-write Hughes’s memoirs and act as go-between for the book’s sale. It’s an offer that no publishing house can refuse and, because of Hughes’s decade long seclusion and notorious mental instability, it’s a collaboration that no one can corroborate.

A handwriting analysis of the letter comes back positive, contracts are signed, and checks are cut. All that remains is the small detail of writing the book, and that’s where “The Hoax” comes to vivid life. During road trips with researcher and co-conspirator Dick Suskind (the always reliable Alfred Molina) to Las Vegas and the Pentagon, the mere mention of Hughes’s name opens doors. A visit to former Hughes aide Noah Dietrich (a marvelously playful Eli Wallach) yields Dietrich’s own unpublished reminiscences on his years with Hughes and the backbone of Irving’s fake book.

Back home, Irving wows the McGraw-Hill boardroom with tales of fictional meetings with the billionaire (which we the audience see re-created before our eyes) and dons a flight suit and fake moustache to help him channel Hughes’s narrative voice into a tape player in the privacy of his own study.

But as art, forged or otherwise, runs afoul of commerce, Irving begins his slow fall from self-made grace. Out of desperation, he sends his Swiss wife, Edith (Marcia Gay Harden, unrecognizable in a blond wig, ski pants, and a pitch-perfect accent), to Zurich to cash checks made out to Hughes. Out of self-loathing, Irving temporarily succeeds at bringing Suskind down to his own adulterous level. Well before Hughes’s debunking phone call, the film says, the jig was up for Irving, a charismatic narcissist who couldn’t distinguish between truth and lies, friends and pawns, wives and lovers, or made-up characters and real people.

“The Hoax,” which is conceptually predicated on the suggestion that Irving’s scam unintentionally toppled the Nixon administration, and is loaded with pop songs, fetishitically re-created 1970s clothes, and gobs of nostalgia (“It’s an Aquarius phenomenon,” Irving says in support of one outrageous claim, “very spiritual”), is pure period biopic hokum through and through. William Wheeler’s script plays fast and loose with facts and dates, and fabricates incidents, characters, and conflicts with a gleeful abandon that has apparently given even Clifford Irving pause. The real Irving, now 76, has reportedly disowned this film version of the book version of his own experiences.

But “The Hoax” is still a hell of a good story, and as Hughes himself suggested, a movie-friendly one. In mainstream middle-brow pictures like “Chocolat” and “The Shipping News,” Mr. Hallström proved himself to be a tidy and clear visual director. His unostentatious directorial ingenuity helps to map out the various levels of subjective reality and points of view that multiply in “The Hoax” as Irving begins to lose his grip on the scam, his deadline, and whether Howard Hughes is or is not participating in the creation of the book.

In this task, Mr. Hallström has a very formidable and unlikely ally in Mr. Gere, who, for the first time in decades, has set aside his posing seducer persona, rolled up his sleeves, and become a warts-and-all character. By giving recognizable human life and dimension to Irving’s manic swings between inexhaustible chutzpah and abject neediness, Mr. Gere makes it possible to empathize with an otherwise unattractive and insecure manipulator, and in doing so has crafted the finest performance of his career.

Outside of Bennett Miller’s “Capote” and a handful of other exceptions, there is usually nothing more static and unrewarding than a movie about a writer writing. Yet Mr. Gere, like Philip Seymour Hoffman in “Capote,” is able to expose the terrifying personal vacuum that is so often the real impetus for inspired acts of creation, especially criminal ones. “The Hoax” may not be the wild, imagination-stretching movie that Hughes predicted, but it’s a visually articulate and expertly performed modern morality play, and, though occasionally silly, remains a memorable and enjoyable film nevertheless.