"L'Atalante," Jean Vigo's 1934 masterpiece about a pair of ardent young newlyweds afloat on a barge down the Seine, is an exhalation of lyric sensuousness. Rapt, exuberant and as fragile as mist, this passionate tone poem drifts in its own bubble of oddly dissonant, almost fatalistic romanticism.

"L'Atalante" is the most perishable of all the great works of the cinema, and the least imposing. There's such innocence and invention in Vigo's style here that the film seems less a consciously constructed work of art than an emanation. No other great master has left behind a smaller body of work than Vigo. In addition to "L'Atalante," his only feature, he made only a couple of documentaries and, in 1933, the 47-minute "Zero for Conduct." The latter, an experiment in free-form storytelling that deals with a revolt at a French boys' school, was considered subversive and was banned from release by government censors.

"L'Atalante," which was released in Paris shortly after the director died of leukemia at 29, is more straightforward in its approach to narrative, but only by comparison to his earlier work. The film begins with the wedding of Jean (Jean Daste), who captains a river barge, and Juliette (Dita Parlo), a peasant girl from a small village on his route. Immediately, after a long and strangely funereal procession through the countryside to the riverbank, the couple separate from their friends onshore and the barge, the L'Atalante, continues its journey down river.

Their companions are the ship's rascally mate, Pere Jules (Michel Simon), and a simple-minded cabin boy (Louis Lefevre). Vigo effortlessly conveys the everydayness of the life onboard. For Juliette, there is virtually nothing to do except deal with the unwashed linens and the disorderly profusion of cats. And shortly, she becomes overwhelmed with boredom. Floating along, she begins to feel disconnected, marginal, as if she were doomed to experience only the edges of her life. "Riverbanks," she says morosely.

The mood Vigo creates here is a kind of enchanted melancholy, and we feel submerged in it the way Juliette does. The effect is almost narcotic. The picture seems to drift, and though almost nothing appears to be happening, our senses are set at a heightened level, as if we were asleep and fully awake at the same time. Vigo moves the story forward by poetic association; there's a logic to the way in which it's ordered, but the links are imperceptible. They're organized by feeling, not intellect.

What's intoxicating about Vigo's style is the way in which the prosaic reality of the life on the barge is charged with luminous undercurrents. Though the love story is at the center of the film, the narrative, such as it is, keeps being commandeered by Simon's Pere Jules or, during the couple's trip to a Paris cafe, the peddler who attempts to entice Juliette into spending a night in the city with him. In one blissful sidetrack, Jules gives Juliette a tour of his cabin, which he maintains as a storehouse of memorabilia from his travels around the world, and as each new bit of exotica is unveiled we're transported far away from the barge's cramped quarters.

Simon's unruly vigor threatens to burst open the seams of the movie's evanescent spirit; you wouldn't be the least bit surprised to learn that he'd been an orangutan in a previous life. Yet without him the movie might slip into a stupor. When Jean discovers that Juliette has slipped away into town, he decides to shove off alone, leaving her deserted on shore where the barge had once been docked.

From this point the film seems to glide to its conclusion on parallel tracks, and every image is suffused with a sense of intolerable longing. Driven half-crazy by Juliette's absence, Jean remembers what his bride had told him about the water revealing your love to you and dives overboard to search for her. Swimming frantically, he has a vision of her floating off in the distance in her white bridal gown, just out of reach.

In its elusiveness and ineffability, that image could stand as a miniature for the whole film -- for that matter, for the director's entire career. As a believer in transcendence and passionate disruption, Vigo was always taking the plunge, following his heart into the ragged margins of life. He had a genius for disorderly, haphazard eloquence, and his dedication to anarchy made it impossible for him to follow the conventional steps. Even in this newly restored version -- which contains some nine minutes of additional footage -- the picture remains magnificently unresolved, an obscure, submerged treasure, gloriously outside our grasp.

L'Atalante, at the Key, is unrated.