Deadpool is a Marvel superhero movie that infuses the usual noble bombast with a welcome dose of grunge. It’s a breezy, synthetic entertainment, nothing more, but with a distinctive tone – a wisecracking graveyard comedy in tights. Its main character, Wade Wilson (Ryan Reynolds), wears an outfit that’s a knockoff of Spider-Man’s, except that you can see the dirt on its red Spandex, and his attitude is even dirtier. When Wade talks (which is more or less all the time), he sounds like the Jim Carrey of 20 years ago – the nattering prankster of Ace Ventura and The Mask – crossed with one of the hellbent wiseacres on a Comedy Central Celebrity Roast, and mixed in with a hint of gangsta rap. He’s a one-man verbal hit squad, tossing off omnisexual rejoinders too naughty to recount here, and he’s also whip-smart. Before administering the coup de grâce to a goon he’s busy beating to a pulp, he says, “I’m about to do to you what Limp Bizkit did to music in the late ‘90s.” One appreciates not just his slasher wit but the spot-on accuracy of his pop judgment.

A former US military assassin who still spits bullets, Wade is scarred, edgy, antic, and maybe a little crazy – the kind of character you would not expect a likable lightweight like Ryan Reynolds to play. But Reynolds, who has already been burned – and badly – by the superhero genre, appears ready not to make the same mistake again. In the misbegotten Green Lantern he was fatally uncool, but in Deadpool he delivers his verbal fusillades with the nonchalance of someone who doesn’t care if he lives or dies, and his slightly fey nihilism is infectious. He invests the act of not giving a damn with conviction.

Behind the mask

In superhero fantasy, there’s a grand tradition of characters, both good and evil – the Hulk, the Joker – who find their physical and spiritual identities through being maimed; their patron saint might be the Phantom of the Opera. In Deadpool, Wade joins this gallery of darkly empowered freaks, but what makes him more than a gloss on the disfigured icons of comic books past is that the film doesn’t just pay lip service to the torments he has to endure. It makes us feel his pain.

Even prior to his transformation, Wade is an alarmingly unhinged badass. He hooks up with Vanessa (Morena Baccarin), who matches his pierced-punk vibe, and they fall into what may be the first romance in movie history to make S&M kink look cuddly. Baccarin, as fiery as she is gorgeous, strikes the kind of sparks with Reynolds that love interests in superhero films too often don’t. When their idyll is interrupted by Wade’s diagnosis of advanced lung cancer, we feel as if we’re in his doomed shoes.

With nothing to lose, Wade joins an underground mutant-superhero program that promises to cure his disease and give him untold powers. The catch? He has to go through the torments of the damned. The leader of the experiment, a smirking sadist named Ajax (Ed Skrein), keeps inventing new physical punishments, so that Wade’s body, in response, will either “mutate or die”. This grisly sequence gives Deadpool a touch of horror beneath its jokey surface. Wade survives, with a body that’s invincible but also with a scarred face that makes him look like the preppy son of Freddy Krueger.

His powers are super, but is Deadpool a hero? He’s recruited by two members of the X-Men but he has no real interest in joining them. And thank goodness for that! Deadpool is a less clunky origin story than we’re used to, and the main reason is that Wade’s agenda has nothing to do with saving the world. He just wants to hunt down Ajax, force him to fix his face, and maybe kill him for kicks.

The film’s first-time director, Tim Miller, gives us opening credits worthy of Mad magazine – one of them reads, “Directed by Some Overpaid Tool” – and he uses schlocky soft rock by Wham! and Peter Cetera to counterpoint scenes of slow-mo mayhem. He also keeps having Reynolds’ Deadpool break the fourth wall: not just by directly addressing the audience but by making fun of other Marvel movies. When Deadpool is on the warpath, his weapon of choice is a pair of ninja swords he uses to turn bad guys into chopped liver, and he’s quite upfront about what he’s doing. It’s not just crime-fighting, it’s murder. The downside of the film’s elemental revenge plot is that it rarely feels like there’s a lot at stake. Deadpool hooks you into Wade’s trauma, but mostly it’s content to skate along on the cheekiness of his death-sport attitude. The film’s airy cynicism says: he’s not the hero we dream of, he’s just the one we deserve.