A life of telling tall tales a bit of a stretcher

Tim Burton -- who made Pee-Wee's Big Adventure, Edward Scissorhands and the first two Batman movies, among others -- is surely one of the most prodigiously imaginative filmmakers around. His best movies glide effortlessly from devilish whimsy to startling perversity, and even when his storytelling falters his inimitably strange visual sensibility leaves its haunting, humorous traces on the memory.

There are, true to form, some startling scenes in his new movie, Big Fish: the hero's arrival in a hamlet called Specter, where the streets are paved with grass and the citizens are always barefoot; his encounter with a witch (Helena Bonham Carter) whose glass eye can reveal the future; his appearance on a campus quadrangle carpeted with daffodils.

The movie also includes, for good measure, a giant named Karl, a squad of circus folk (led by Danny DeVito), a pair of conjoined Korean twins and some menacing, anthropomorphic trees.

The theme of Big Fish, adapted by John August from the novel by Daniel Wallace, is the transforming power of the imagination, which would seem to be a natural subject for Burton. But the most curious thing about this magical-realist fable is how thin and soft it is, how unpersuasive and ultimately forgettable even its most strenuous inventions turn out to be.

The hero is Edward Bloom, a traveling salesman, who, though he comes from a small town in Alabama, is played as a young man by Ewan McGregor, who is Scottish, and in his later years by Albert Finney, who is English. These two actors (their Southern accents, by the way, are not bad at all) share a robust sense of mischief that overcomes their physical differences. You have no trouble imagining McGregor mellowing and thickening into Finney.

Edward, who personifies the bumptious, mythic American life force, is devoted to shading and embellishing the truth. He is an inveterate spinner of what Tom Sawyer, one of his literary ancestors, liked to call stretchers. Edward's oft-repeated, never-veri-fied tall tales, including his signature yarn, the fish story that gives the movie its title, are endlessly charming, except to his son, Will (Billy Crudup), who finds them so exasperating that he stops speaking to his father for several years.

Will is a news-agency reporter in Paris, a suitably empirical profession for the rebellious son of a fabulist father. A phone call summons Will back home to Alabama for a deathbed reconciliation, during which Edward elaborates his fairy-tale biography.

In his telling, the usual stations of the life cycle -- departure from home, courtship (of the lovely Alison Lohman, whose character ages gracefully into Jessica Lange), fatherhood, an accidental foray into crime -- become wild episodes in a sprawling picaresque adventure. If only. Even though Will's warmhearted French wife (Marion Cotillard) and his soft-eyed mother (Lange) hang indulgently on Edward's every word, his stories are so labored, so self-flattering and ultimately so pointless that it is hard not to feel some sympathy for Will, who grew up in his father's shadow and, for much of his childhood, in his absence.

From time to time, a glimmer of real drama shines through all the twinkly sentiment. The conflict between father and son is the most, perhaps the only, believable element in the story, but the movie is so thoroughly bewitched by Edward that it makes Will look like a cold fish who stubbornly refuses to accept his father for what he is.