Water and glass are the dominant metaphors of Gillian Armstrong's adaptation of Peter Carey's Booker Prize-winning novel Oscar and Lucinda, and though the film captures the superficial beauty of these materials, it doesn't penetrate beyond their glistening transparency. This is partly the fault of the novel, which despite its lofty themes of obsession, faith, and fate, its splendid prose, and its elfin absurdity, is essentially a lengthy caprice. Armstrong's version emphasizes the cuteness and farce at the expense of the substance.

Set in the 19th century, it's the story of Oscar Hopkins, only son of Theophilus (Clive Russell), a bearded and fulminating fundamentalist preacher in a small town on the Devon coast. In brief episodes that are among the film's most magical moments, Armstrong blithely recounts Oscar's childhood. In an astonishing scene, he pursues his father to the sea after his mother's death, where Theophilus in maddened grief hurls the dead woman's clothes into the surf -- the origin of Oscar's water phobia. Later, after being punished for eating the "Devil's food" of Christmas pudding, young Oscar determines that his father is "in error," and after a hopscotch-like exercise in thaumaturgy decides to join up with the diminished flock of Reverend Hugh Stratton (Tom Wilkinson), Theophilus's Anglican rival.

Such games of chance prove fateful for Oscar, played as an adult by a goofy, carrot-topped Ralph Fiennes. As a student at his adopted father's college in Oxford, he's introduced to gambling by Wardley-Fish (Barnaby Kay, in one of the film's few non-caricaturish supporting roles); he's a natural at it, to his embarrassment and spiritual horror. As penance, he volunteers for service in the primitive Outback of Australia. En route aboard the ominously named Leviathan, he meets his soulmate and downfall, Lucinda Leplastrier (an earthily ethereal Cate Blanchett).

An heiress who has spent her fortune on a Sydney glassworks, Lucinda shares Oscar's gambling addiction and innate nonconformity. She's a pre-feminist (she wears bloomers; when matched with Oscar in his ill-fitting hand-me-downs they look like a beanpole Raggedy Ann and Andy) whose socially unacceptable attitudes and nightlife have already earned the exile of her friend Reverend Dennis Hasset (Ciaran Hinds) to a remote, church-less parish called Never-Never. She proves Oscar's undoing as well with their high-stakes unconsummated dalliance. Apropos of little, Oscar vows to prove his love to Lucinda by transporting a glass chapel over dangerous terrain to her seeming swain Hasset's new residence.

Such a belabored metaphor has been attempted before -- the opera house on the Amazon in Werner Herzog's Fitzcarraldo. And as in that film, the conceit succumbs to its own self-conscious contrivance. As Oscar and his party plunge deeper into the wilderness, the film bogs down in the weighty issues of imperialism and genocide -- the clash with its earlier tone of whimsical cartoonish satire is jarring. Although the epiphanic image of a somber Oscar seated in the elegant glass church as it floats down a river makes the ordeal nearly worthwhile, it's too fragile a craft for the film's weighty symbolic cargo. At the Nickelodeon, the Harvard Square, and the West Newton and in the suburbs.