That rainbow bridge links Thor's homeland of Asgard to the various worlds surrounding it, including Earth. When we first arrive in Asgard (after a dodgy prologue detailing a previous conflict with the Ice Giants), it is a day of celebration, with Odin (Anthony Hopkins) preparing to announce his eldest son Thor (Chris Hemsworth) as his successor. The ceremony is interrupted by those pesky Ice Giants, and after Thor reveals his tempestuousness by defying his father's instructions and declaring war on Asgard's foes, he is stripped of his power and banished to Earth, which leaves his devious younger brother Loki (Tom Hiddleston) free to make his own grab for power back on Asgard.
There you have it. The plot, with all of its mythical and oedipal undertones, has been set in motion, and after the overstuffed calamity that was Iron Man 2, such a clean narrative comes as a blessed relief. Thor is unlike anything Branagh has directed before, but in an early action sequence on the planet of the Ice Giants he shows he's got what it takes, directing in a lively, punchy fashion. There is less action in Thor than you might expect, however, and when the main protagonist is sent to earth it takes on the shape of a 'fish out of water' comedy. Hemsworth, who is suitably brash as the all-powerful God of Thunder, also shows a light touch in the film's comedic aspects. In fact, the performances are Thor's strongest suit, and the aspect of the film in which Branagh's influence is most recognisable. He directs commanding performances from the three main actors in the film – Hemsworth, Hiddleston and Hopkins – imbuing the dynamic between them with a real sense of gravitas. Some of the supporting characters in the film are admittedly poorly defined; Thor's teammates never come to life, Rene Russo (hello again!) is entirely wasted, and Natalie Portman's Jane isn't strong enough to give the intended love story some any weight. Branagh pins everything on that central trio, though, and they succeed in grounding the fantasy in a kind of relatable reality.
Perhaps the most refreshing aspect of Thor is that it never forgets to be fun, and in an age when "darker" appears to be the watchword for comic book movies, the film's bright design and the gusto with which Branagh directs makes it a pleasing anomaly. Although it runs for more than two hours, I was never bored with Thor, finding it a hugely satisfying and accomplished blockbuster...but then the credits rolled and The Avengers loomed into view again. Look, I know plenty of people are excited about the crossover potential for this series, but I fear superhero overkill will retroactively diminish Thor's achievement. Branagh's picture works brilliantly as a standalone comic book film, but of course it isn't a standalone film, and I do worry that we'll be sick of Thor and his fellow Marvel buddies by the time The Avengers and the inevitable sequels start filling the summer schedules.