Will Smith's powers are even more extraordinary than those of a caped crusader who can leap way beyond the tallest buildings in a single bound. Smith has salvaged many vehicles more threadbare than "Hancock," and though his latest venture is decidedly uneven, he seems poised to score yet another supervictory at the box office when it opens July 2. The Columbia Pictures release is a good showcase for him -- and for co-stars Charlize Theron and Jason Bateman. Imagine the heights they all could have scaled if the picture had been really good.

One suspects that the movie's problems stem from the multitude of cooks who toiled on the project during the several years it took to reach the screen. Although the script is credited to Vy Vincent Ngo and Vince Gilligan, several others worked on it, including producers Akiva Goldsman and Michael Mann. Jonathan Mostow and Gabriele Muccino were among the directors attached to the project before Peter Berg signed on. Somewhere along the way, a sharp black comedy lost its bite.

The movie's sly premise is established in its opening scenes, which reflect the tart sensibility of Gilligan, the creator of AMC's bracingly cynical series "Breaking Bad." Hancock is a crime-fighter going through what appears to be a midlife crisis. He's a foulmouthed drunk who springs into action when Los Angeles is in trouble, but he behaves with such wanton disregard for people and property that he often alienates the citizens whose lives he saves.

When Hancock rescues an idealistic PR man (now there's an oxymoron), the grateful Ray (Bateman) embarks on a campaign to burnish Hancock's bad-boy image. The benevolent publicist -- the antithesis of Tony Curtis' sleazy Sidney Falco in "Sweet Smell of Success" -- is another choice comic character. The movie introduces a third when Hancock meets Ray's wife, Mary (Theron). There are mysterious sparks between the loutish superhero and the pert suburban housewife, and it's clear that Mary has some connection to Hancock's past. But this is where the movie starts to unravel. It veers from comedy to romantic tragedy and introduces an elaborate backstory that never makes much sense.

The best comic book movies develop a rigorous and logical mythology. As "Hancock" races toward its spectacular but muddled finale, it keeps rewriting its own rules in an effort to pander to the audience. The storytelling lapses are not helped by Berg's frenetic direction. As he showed in his most recent film, "The Kingdom," Berg is addicted to intense close-ups and kinetic hand-held camera movement. He seems to be worshiping at the altar of Michael Bay.

Berg's strength lies in his appreciation for actors and keen eye for casting. Bateman has brightened many recent movies, including "Juno" and "The Promotion," but no one has given him such a juicy part in years. The actor rips into it lustily. British actor Eddie Marsan (a member of Mike Leigh's stock company) also makes a strong impression as a genuinely creepy villain.

Special effects supervised by veteran John Dykstra are at once witty and eye-popping. In keeping with the concept of the surly superhero, Hancock makes his entrances and exits spewing mounds of concrete in his hazardous wake. The visual effects are stellar, but the true star is Smith, who again demonstrates acting chops as well as effortless charisma in a vehicle that's only occasionally worthy of his superhuman skills.