John Hancock uses side streets as launching pads to soar through Los Angeles, tosses criminals aside as if they were tin cans and sips whiskey from a jug while villains futilely shoot bullets at him.

Great powers, but Hancock’s had it with great responsibility. People expect a man capable of flight and indestructibility to save the day without complaint. He’d rather be drunk and disorderly.

And while Hancock’s body never ages, neither does a troubling memory always fresh at the front of his mind: 80 years ago, he awoke alone in a Miami hospital, not knowing who he was, with no one willing to claim him and just a pack of gum and two tickets to Frankenstein in his pockets.

That’s an apt piece of movie nostalgia to toss into Hancock, which stars Will Smith as the slovenly superhero. But it’s not because this blockbuster mines the mournful, misunderstood subtext of a man unwittingly created. That’s because it feels thrown together from an assembly of half-functional parts, electrified by a multimillion budget and left to lurch to life only on occasion.

Smith delivers his usually compelling blend of comedy and pathos; he makes the line “Got a toilet?” sound like a threat that Glade won’t eradicate. But he can only do so much for what becomes the 90 strangest minutes of the summer — 60 dedicated to a jaunty, attitudinal mix of action and comedy seen in the film’s trailers and 30 devoted to a grab-bag of haphazard drama.

Hancock is hard to dissect without at least a cursory mention of its hard-to-digest third act, which attempts to turn modestly enjoyable product into resonant poetry. With so much clumsy telegraphing, it’s not surprising where Hancock goes. The shocker is a rushed pace and lack of focus, to the point where it would seem better off as a sprawling, epic novel similar to Michael Chabon’s The Adventures of Kavalier and Clay.

Ideas of fate, mythology and, yes, even racism in America are haphazardly thrown in for weight amid a climactic gunfight so grim that it’s like watching Men in Black morph into Requiem for a Dream. That wouldn’t be a problem if director Peter Berg’s film had breathing room to earn such a gritty feel, but Hancock seems like a hack-and-slash job from earlier, less-commercial drafts.

The film opens with a freeway shootout lazily reminiscent of Berg’s The Kingdom, replacing terrorists with gang members. Passed out on a bench, Hancock is reluctantly shaken to action by a kid and intervenes … to the tune of $9 million in damages. A warrant is issued for Hancock’s arrest, but it’s just the latest round of bad press. And there’s even more after he saves PR man Ray (Jason Bateman) from an oncoming train.

It’s no longer impressive to see a man fling a car, as Hancock does to save Ray’s life. Innocent bystanders aren’t so innocent anymore, armchair Superman-ing everything Hancock does. Hancock carries one of its biggest charges in this scene’s satirical disillusionment with superheroes, as the angry mob questions the trajectory Hancock used to toss Ray’s car.

But Ray seizes the opportunity, down on his luck as he is pitching charities to corporations. In Hancock, he sees civic duty, a defining professional project and a way to repay a favor.

Agreeing to make over Hancock’s image, Ray insists Hancock serve the jail time city fathers are calling for. After all, it’s just a matter of time before a skyrocketing crime rate gets him pardoned and, ridiculous superhero suit and all, the “new” Hancock gets his shot at redemption. (Smith’s deadpan skills are brilliant in a sequence spoofing extremes of PC behavior a la The Incredibles.)

What seems like an easy plan becomes complicated, though, once sparks start to fly between Hancock and Ray’s wife, Mary (Charlize Theron, whose eyes either look watery, angry or wangry).

Berg’s jittery handheld camera puts actors’ faces in audiences’ laps, and in Hancock’s best exchanges, that method jumpstarts banter between Smith and Bateman (in fine form as usual). Mostly, it’s out of place amid flying effects akin to the cheap-looking My Super Ex-Girlfriend.

It’s indicative of the movie’s problem of trying too much in too little time: a thunderous action film, a quirky comedy, a psychological character study of a man who’d rather crawl away and hide than serve and protect, a social commentary on how we build up, and tear down, heroes.

With only 82 minutes before credits for all of that, something’s got to give. Rather than ink its signature as a study of the social problems superheroes might face, Hancock is content to just slam its plot into walls along with the bad guys.