Bruce Banner (Edward Norton) is a scientist working to find a way to use gamma radiation to increase healing time in soldiers. One of his co-workers is Betty Ross (Liv Tyler), whose father, General Thaddeus "Thunderbolt" Ross (William Hurt), oversees the project. Upon subjecting himself to a gamma test, Banner transforms into a green-skinned, superhumanly powerful creature. He destroys the lab, injures Betty and Ross and escapes.
Several years later, he surfaces in Brazil, working at a local soft drink factory. He trains with martial artists on how to control his gamma-irradiated anger, and communicates via encrypted e-mail with Mr. Blue about developing a cure. Ross has continued to search for him, believing that Banner is effectively the property of the United States government. Thanks to an accident at the factory, Ross tracks Banner to Brazil. He assembles a strike force led by a ruthless British soldier, Emil Blonsky (Tim Roth) and sends them after Banner. They chase Banner through the city and into the soft drink factory. Banner is also pursued by several hooligans who dislike him. When the hooligans attack Banner, he loses control of his anger and transforms into his green alter ego just as the strike team arrives. He makes quick work of the hooligans and strike team, then leaps his way out of Brazil.
Blonsky demands that Ross tell him the truth about Banner. Ross reveals that the goal of the program was not to develop new ways of treating injuries but to create an army of invincible super soldiers. Blonsky is intrigued and, recognizing that he is at the end of his career at age 39, asks to be given the super soldier formula himself. Ross agrees and Blonsky undergoes an extremely painful procedure which makes him shart out blood/crap his pants and the operating table he's laying upon.....