The reckless actions of the mighty Thor (Chris Hemsworth), a powerful but arrogant warrior, reignites an ancient war. Thor is cast down to Earth by his father Odin (Anthony Hopkins) and is forced to live among humans. A beautiful, young scientist, Jane Foster (Natalie Portman), has a profound effect on Thor, as she ultimately becomes his first love. It’s while here on Earth that Thor learns what it takes to be a true hero when the most dangerous villain of his world sends the darkest forces of Asgard to invade Earth.

A solid, if somewhat uninspired, comic book adaptation.

Somewhere in the avalanche of publicity material generated by this latest Marvel comic book adaptation actor Chris Hemsworth declared that the filmmakers aimed to '"¦keep it real." Reality can be relative, especially in actor movie-speak. In the film, Hemsworth plays Thor, the god of thunder, a character based on the Norse legend, created by Stan Lee, Larry Leiber and Jack Kirby. Thor first appeared in a Marvel Comic in 1962 and became a regular character for MC publications in his own adventures before taking up duties as one of The Avengers, once that comic series got going.

Lee liked the Viking image for this superhero, who was stronger than, well, anyone: the breastplate, the cape, the horned helmets and the big hammer. If 'keeping it real’ means that an actor can carry off this outfit without inspiring derision then Hemsworth nails it.

Distilled to essentials, the plot of the film is pure MC; it asks what would happen if a god, rightful heir to his kingdom in the heavens, was stripped of his powers and his honour and was exiled to Earth?

Part of the fun of comic fiction is its interest in complicating simple plots with elaborate and dense detail. To reproduce that ambience in a film can make it long, confusing and top-heavy. One of the best things about Thor is that in spite of the fact that there’s loads of action, characters and bits and pieces to keep clear in your head, it never feels overloaded. It kicks along, but the elaborate back story is still there. It’s also big, loud, and heavy with CGI and 3D effects. Still, if the filmic techniques are photo-real, there’s something odd and abstract about the world of the film; its surface seems deliberately artificial like a fairytale pop-up book come to life.

The film’s action is divided between scenes set in Thor’s home of Asgard, and Earth. The 'heavenly’ plotline is a story of succession and sibling rivalry; King Odin (Anthony Hopkins) must chose between sons Thor and Loki (Tom Hiddleston). Thor is hot-tempered; he seeks revenge against the Frosties, sworn enemy of his kingdom. Meanwhile, there’s something distinctly sleazy and traitorous about Loki, and it isn’t the permanently raised eyebrows or the black cape. (Cheap-gags aside, Hiddleston brings a dignified intensity to his part, that’s quite touching in a way.)

Thor’s action infuriates his dad, who fought a terrible war against the Frosties, which ended in a truce and a lasting peace. It’s at this point that Thor loses his hammer and is exiled to New Mexico, USA (and later the hammer ends up there, too).

The Earthbound story is dominated by a romance subplot with a nod or two to blockbusters of yore like The Terminator and Back to the Future. Or, to put it another way, the tone is ironic, a little playful and choc full of set pieces derived from some well-known legends (including Arthur and his knights). There’s plenty of pop culture references and movie homages too, and a few stray characters from the Marvel universe intervene briefly on the action.

It’s after dropping into the desert via a sort of cosmic super-conductor that Thor meets Jane (Natalie Portman), an astrophysicist who is engaged in a project studying a series of disturbances in the stars. She takes one look at Thor’s pecs and starts to giggle at the mathematical possibilities. Meanwhile, back in Asgard, Loki plots to take the throne from Thor. Jane sets out to help Thor get his hammer back; and he teaches Jane a thing or two about heavenly configurations. (That’s no joke – he explains the position of each realm of the universe, sketching it out for her in a notebook.)

Hemsworth is particularly good in the New Mexico scenes; maybe because he doesn’t have to play most of them in a cape. His look here – too tight t-shirt and jeans – is more designer trailer-park hot-dude, while his attitude is a happy mix of innocent stranger and quiet tough guy.

The net has been full of talk about Marvel’s choice of Kenneth Branagh as director, famous for his rather over-rated Shakespeare films Henry V and Hamlet. Never a helmer who showed any talent or even interest in visceral excitement or spectacle, Branagh certainly seems an odd choice. Indeed the fans were right to worry; the action, settings and pacing of the film is not the work of someone with any obvious gifts for genre filmmaking. Asgard’s design looks like it was inspired by the kind of fantasy murals motor-heads paint on their street machines and the sets, enormous constructs are like the '70s sci-fi of Richard Donner’s Superman. The action isn’t bad exactly, just uninspired. Branagh and co. cover the mayhem with camera pyrotechnics that have become clichés since Peter Jackson’s Ring films, like panoramic landscape fly-around travelling shots, fast-tracking into flying fists, and rapid fire edits so fast it’s impossible to get a sense of who’s who and what’s what. Still, by the climax, the action settles into style that is executed with a fine sense of dynamics where the camera moves, explosions and choreography are tuned perfectly to deliver tension and release.

Best of all, Branagh achieves a feel for the material here that’s pretty charming. Maybe that’s what Hemsworth was talking about after all. The actors don’t patronise the material or camp it up. It seems grandiose to talk of emotional authenticity in the case of a movie like Thor but the actors actually seem involved in the characters and the story. You don’t feel like they’re laughing on the inside. It’s involving and that’s always fun.