D: Shane Black. S: Drew Pearce, Shane Black. P: Kevin Feige. Cast: Robert Downey Jr, Guy Pearce, Gwyneth Paltrow, Ben Kingsley, Don Cheadle, Rebecca Hall, Jon Favreau. UK dist (Blu-ray/DVD): Paramount.

Movie superheroes. Generally speaking, a rowdy bunch of underachievers. Of the recent swathe of Marvel tie-ins, only the Iron Man franchise has proven consistently worthwhile, thanks largely to the casting coup of Robert Downey Jr and some occasional flashes of wit. This third instalment is really the fourth, since industrialist Tony Stark’s last appearance was in the Marvel mash-up Avengers Assemble (a.k.a. The Avengers, 2012), an excellent example of what the comic-book genre can achieve when it gets off its arse. As Iron Man 3 kicks off, Stark – impossibly wealthy techno-wizard, and inventor of the Iron Man™ robo-suit (basically an Art Deco F-16 jet, in humanoid form) – is suffering periodic anxiety attacks, following his alien encounter in the previous film. Stark is forced to get his act together when a new threat manifests itself, in the form of fanatical terrorist The Mandarin (Osama Ben Kingsley), who promises all-out war on the US in a series of doom-laden propaganda broadcasts. When the Mandarin’s forces destroy his home, Stark is forced to flee with only a prototype Iron Man suit, low on power. Meanwhile, Aldrich Killian (Guy Pearce) – a geeky genius whom Stark once snubbed – has reappeared on the scene, having reinvented himself with a new formula which turns seven-stone wimps into lava-breathing supermen. Could Killian and the Mandarin be connected in some way…?

Beside the bloated cluelessness of most big-budget comic-strips, Iron Man 3’s breezy charm is a breath of fresh air. Director Shane Black – who also teamed up with RDJ on the snarky noir gem Kiss Kiss Bang Bang in 2005 (and, of course, first made a name for himself with a series of sharp action-movie scripts for various Die Hards, Lethal Weapons and so on) – has a real knack for comic byplay and punchy action set-pieces; the helicopter gunship attack on Tony Stark’s modernist cliffside pad is particularly good. Black also knows how to undercut the portentous clichés of the superhero genre with a well-timed visual gag: during the climactic battle, we watch Stark’s autonomous Iron Man suit assemble itself in mid-air and race towards him across the battlefield, ready to spew high-tech firepower in the nick of time…only to clang into a steel girder at the last moment and break into a pile of rubble.

Dipping casually into his bottomless well of charisma, Robert Downey Jris on fine form as Billionaire Playboy Philathropist Inventor Tony Stark (to give him his full title). It’s been said before, but this is a role RDJ was born to play: as the boyish, wisecracking genius, restlessly tinkering with his toys,he’s totally credible. Sure, it’s a comic-book role – but there’s a knack to playing this kind of part. Stark could easily have come off as trite and one-dimensional, but thanks to RDJ’s easy charm the role works like a dream. Guy Pearce likewise hits all the right notes as the bronzed, self-made Evil Adonis, turning amputees into supermen to further his ends. Even Gwyneth Paltrow’s Pepper Potts actually does something this time around, instead of just winsomely frowning; transformed into one of Pearce’s magma-blooded hybrids, she doles out CGI mayhem with the best of ‘em. But effortlessly swiping the acting laurels is Ben Kingsley, alternately terrifying and hilarious as the Blood-and-Thunder Jihadist kingpin who (in one of the film’s funniest moments) turns out to be, in fact, a meek British thesp giving the performance of his life. (“His Lear was the toast of Croydon”, remarks Pearce. “Wherever that is.”)

While not flat-out great, Iron Man 3 is uncomplicated fun. Yeah, the villain’s scheme is a bit vague, and the finale over-reliant on a technological deus ex machina – but the cast is on fire, the effects mostly good (though, as usual for CG, too cartoony at times) and the score suitably catchy. You could do a lot worse.