Moviegoers flocked to M. Night Shyamalan's new film "Unbreakable" when it opened across the country recently, much as they did last year to his first film "The Sixth Sense," but I'm not sure they're going to keep it up this time. "Unbreakable" has the same supernatural underpinning, but it lacks the depth and power and internal logic that gave "The Sixth Sense" its incredible and well-deserved appeal.

The film tells the story of David Dunn (Bruce Willis), a security guard at the University of Pennsylvania stadium, who somehow survives a train crash that kills everyone else on board. He doesn't know why he survived, and the film slowly brings him and us to an understanding of what makes him apparently 'unbreakable.' He finds himself drawn to a reclusive man, Elijah Price (Samuel L. Jackson), who owns a gallery that specializes in comic book art, and who, unlike Dunn, is cursed with a body that seems to constantly break.

Dunn has separated from his wife Audrey (Robin Wright), though they still share the same house, with Audrey downstairs and David upstairs along with their young son Joseph (Spencer Treat Clark). The couple seem almost mute with each other; David is barely verbal, and it is only through others that we learn that he was a star college athlete, that his present job is much less than he could handle, and so on. In fact he is so depressed that he appears to move through oatmeal rather than through air.

But what specifically fascinates Elijah is that David seems to be physically 'unbreakable' in every instance where others might be injured or ill, and so he keeps after him to examine why that is. Slowly David, Elijah, and the audience come to learn the truth about him, and about Elijah as well.

It's a brave and bold conceit for a film, and a not unworthy followup to "The Sixth Sense," but unhappily Shyamalan doesn't give this one the solid underpinning of believability he gave that brilliant ghost story. He hasn't fleshed out his characters this time, so when the denouement comes here, we just don't care enough for his people. Contrast this with "The Sixth Sense," in which the audience comes to love not just the Willis and Osment characters but almost all the people in the film, and "Unbreakable" has an enormous hole at its center.

There is a problem, too, with the direction. Shyamalan has directed Willis to play almost as an automaton, a sleepwalker who can barely put two sentences together; but he hasn't justified that in the script, so David Dunn becomes simply a boring, uninteresting person to us. If we contrast this with his child psychologist in "Sixth Sense," a man consumed with understanding something, someone, outside himself, a man with a personality and a profession, we see the weakness in this film. It's no wonder that David's wife has separated from him.

Near the end of the film, Shyamalan almost redeems himself with a bravura episode in which David spots a potential criminal and decides to follow him. It almost, though not quite, pulls the whole film together, tying up Elijah and his comic books with David's 'unbreakable' quality and his personal history, uniting the surreal and the supernatural that are at the core of the film. It's a brilliantly realized sequence that requires the audience to look hard and think about what's going on. Nevertheless it does not make up for the shallowness of the film as a whole.

I've picked on problems of depth and Shyamalan's incomplete, even sketchy filmmaking here, but these are flaws in the work of a marvelous artist. He has control in every frame of every shot of every scene, lighting and shooting them with impeccable skill. He sees even the most common conventions of filmmaking as brand-new challenges. Rain isn't just rain; it has cosmic overtones. A man disappears around a corner, but we only saw him for two frames before he was gone. Shyamalan knows how to shoot a movie, and edit it, as well as anyone ever has. That's quite a talent.