Norton plays Dr Bruce Banner, the scientist who has been irradiated (or whatever the back story is this time) and turns into the big green monster whenever his heart rate gets over two hundred beats per minute. When the film begins, Banner is hiding out in Brazil, looking for a rare flower that could hold a potential cure, as recommended to him by his online friend "Mr Blue".
Unfortunately, events catch up with Banner and he soon has to leave Brazil with the US military hot on his heels, because they want to capture the Hulk and find a way to weaponise his blood. Banner decides to head back to the USA after five years of being on the run (it's been five years since Ang Lee released his Hulk film) to meet with "Mr Blue" and further investigate a potential cure for his condition.
Menawhile, Tim Roth (Reservoir Dogs) is shaping up to become a super soldier himself by volunteering to be injected with some super serum from the Second World War. It will come as no surprise that he eventually turns out to be a bad guy, I'm sure.
What makes this a good film, however, is the mixture of violence and explosions (albeit mostly unrelated to the main story) and the character depth displayed by Norton and his ex-girlfriend played by Liv Tyler (Lord of the Rings). The director, Louis Leterrier, has so far proven to be a bit of a hack on films such as Transporter 2 and Unleashed, but he has shown here that he is capable of slightly more.
The decent character progression is more likely the result of a good screenplay, however this one was written by the aptly named Zak Penn, who has proven that he is capable of writing comic book movies (Elektra, Fantastic Four, X-Men: The Last Stand), he's just not capable of writing very good ones.
All of which brings me back to my original point. It looks like the reason for this film's success is Edward Norton, who not only does a good job as an actor, but who also rewrote the script before shooting began and continued to tweak it during production.
The result is a film that is less about the Hulk vs. another monster and more about Bruce Banner's personal struggle with a power he can't control and his desire to find a cure rather than attempt to deal with what he has become. And there are lots of fights and explosions in it too. So, it's no Iron Man, but as comic book films go, it's definitely worth watching.