The idea sounds ripe: Will Smith, one of the screen's most engaging movie stars, playing a surly wino of a superhero, making a mess of Los Angeles as he comes to the occasional aid of those in need. But not even Smith's charisma can mitigate the chaos that is "Hancock."

It depresses me to think of all the preteens who'll be sitting through this, since it squeaked by with a PG-13 rating; the violence and the general abrasiveness are a genuine drag. Then again, adults won't be much better off. In this highly superheroic summer of "Iron Man" and the forthcoming "The Dark Knight," "Hancock" can offer only an A-list headliner in a D-list project.

The notion is that a vaguely self-loathing superhero, who spends his days flying around Los Angeles and taking care of its assault-weapon-toting vermin, suffers from self-esteem issues that prevent him from being the best he can be.

Enter a public relations whiz (Jason Bateman), whom Hancock saves from a collision with a train. The PR man, despite the protestations of his wife (Charlize Theron), takes on Hancock as his latest project. The flack makes Hancock, who doesn't know how he gained his special powers, see the value in soft, non-destructive landings and the odd kind word.

Halfway through, screenwriters Vy Vincent Ngo and Vince Gilligan dump a huge load of superhero backstory onto the movie's doorstep. Director Peter Berg and his cinematographer shoot a lot of "Hancock" in gritty, nausea-inducing close-up, and the effects -- aurally bombastic, visually ordinary -- sit on the action in all the wrong ways. Why shoot this film like an R-rated action thriller? What good does all the nastiness do except to rough up an audience like a corrupt cop interrogating a suspect?

Pro that he is, Smith doesn't dog a minute of it. He's such an easygoing presence, he periodically humanizes the material. His name alone may well ensure a profitable week or two for "Hancock." But like "Last Action Hero" and "My Super Ex-Girlfriend," this is a film searching, desperately, for the right stylization and the right tone. The sight gag destined to be the film's talking point involves a man with his head rammed up another man's hindquarters. And if you don't like hearing about it, don't let your kids see it.