And so, after all the advance jungle drums, Cast Away is not about how Tom Hanks lost weight to play Chuck Noland, a FedEx employee marooned for four years on a South Sea island when his delivery plane crashes in a storm — although his physical transformation is indeed impressive. It's not about whether the power of a survivor movie is diluted by such recent, high-intensity exposure to the Survivor TV series — although both suspenseful sagas demonstrate how to start a fire and spear a fish. It's not even about the jarring tragicomedy of seeing Hanks in a Hanksian one-sided dialogue with a volleyball — although the loyalty and intimacy with which Noland treats the inanimate friend he calls Wilson (painting a face on the ball in his own blood) is effectively harrowing in its desperation and primal instinct to connect.

Rather, as the sun sets, Cast Away is about the infinite gulf that separates the words cast and away, and this is what elevates the story from the realm of Gilligan's Island to the more ambitious epic territory of a contemporary, masculine, existential meditation. In that vast horizonless space — as awesome a place on earth, director Robert Zemeckis suggests, as it is in the heavens of his Contact — a man can find his clock stopped and when it restarts he is no longer in time.

''I'll be right back,'' Noland assures his girlfriend, Kelly (Helen Hunt), before boarding an ill-fated plane. It's Christmas Eve, and in a swap O. Henry might have arranged, he's just given her a tiny wrapped box — presumably an engagement ring — while she's given him her grandfather's pocket watch with her photo inside. The ticking clock means everything for Noland, an efficiency expert too busy to slot in a proper proposal of marriage. ''Let us not commit the sin of turning our back on time!'' he lectures some slack Russian colleagues, whipping a Moscow shipping outpost into shape. The scene jumps smartly to the soundtrack accompaniment of the Red Army Choir.

Before Russia, though, in the first scene of the movie, Zemeckis has already begun messing with the elasticity of time, opening with an exquisitely slow tracking shot down a Texas rural route to a crossroads — Nowhere and Everywhere — at which a FedEx truck makes a wide right turn to Somewhere. The Russian detour picks up the tempo. The humdrum takeoff pace of the doomed plane slows it down again, imitating the remarkable everydayness of flight. The ocean crash that follows explodes into chaos, a clenching tumult of darkness and roaring sound that alternates with deathly silence reminiscent of the underwater eternity in the opening of Saving Private Ryan.

And then: sunlight. Desert island. And for a very long time, Cast Away is about nothing so mesmerizing or so daring as its sustained attentiveness to the silent activity of a man engrossed in teaching himself how to survive. The FedEx boxes that wash up provide potluck tools: Ice-skate blades become a knife; videotape becomes rope; the voile netting from a fancy dress is fashioned into a fishing net.

This lonely idyll is carried out utterly solo by Hanks, in the strips of cloth Noland fashions into bandages and coverings. Just Hanks trusting the director who trusted him to span time in Forrest Gump, and each being repaid manifold in their trust. Hanks towers as a near-naked, near-biblical man. Zemeckis tells his story — the screenplay is by William Broyles Jr. — with a control magnificent in what isn't shown as much as in what is.

And then: Noland is back home, taking stock of what's lost and who's lost. And here, only here and now, does Cast Away stumble, just as Noland does, blinking in the paralyzing light of reentry. Affected perhaps beyond words, but no longer in a place where only actions matter, the hero and the filmmaker who shaped him bump up against the rim of the movie's world, fumbling to tell of the loneliness of those who feel marooned even with friends nearby. What does it say that this modern parable finds it hardest to convey the intensity of an average love affair, that the wisdom of eternity can't help a guy decide which way to turn at a crossroads? A-