Over the opening credits, we see how the Hulk was born. Bruce Banner (Edward Norton) is a scientist working on a project involving making the body resistant to certain types of radiation.
Working with him is fellow scientist and love interest Betty Ross (Liv Tyler). The project is centered around the use of gamma rays, the most harmful kind - lead sheets required.
However, something went wrong, and we see him destroying the lab and killing some other scientists.
He also injures the project overseer, General Thaddeus Thunderbolt Ross (William Hurt), and rendering Betty Ross, the General's daughter, unconscious.
A little later, we see Bruce at the bedside of Betty, who is wavering in and out of consciousness, when suddenly Ross is there with his arm in a sling, screaming at Bruce. Bruce flees, and the hunt begins as Ross tracks down every possible lead he can find on the location of Banner and what lies within him.
158 DAYS WITHOUT INCIDENT
In a town in Brazil, Bruce wakes up from a nightmare of everything thats happened to him. He groans and goes about his morning routine, which includes feeding his dog Rick and learning Portuguese by watching Sesame Street and comparing what he hears to a Portuguese-English dictionary.
He also spends time learning relaxation techniques in an effort to control his heart-rate and keep himself from becoming too excited.
He goes to his job as a day laborer at a local factory, handing out dry goods and cleaning up messes while avoiding the old tough guys at a bottling factory. He also occasionally helps out with the electrical aspects when something breaks, which it does today.
As he's fixing it and joking around with the manager, he cuts himself on a metal clip and the blood falls through the grated floors onto the belt, and Bruce freaks out, yelling for the belt to stop. Confused, the workers stop the belt and Bruce inspects the area where the blood fell, cleaning it up and giving it the okay.
As the belt starts and people start talking about the crazy gringo, no one notices the drop of blood that fell into a bottle currently destined for the United States of America. Unaware of the contaminated bottle, Bruce starts to leave, but notices the same toughs who usually give him a hard time coming on to an attractive co-worker, Martina.
Bruce stops the action by asking Martina if she'd like to have lunch with him tomorrow, but the leader of the gang gets in Banner's face, who cautions the leader in Portuguese by saying, "Don't make me hungry. You wouldn't like me when I'm hungry."
Confused, Bruce goes over this just as the manager pops up, enabling him to escape a beating and head for home, stopping along the way to pick up a package from someone. Once there, Bruce boots up his homemade computer and makes contact with someone named Mr. Blue in America.
Together, the two of them are working on a cure to Banner's problem, and after dicing up the flowers that were in the package, he applies its juice to his blood.
Bruce regretfully types, "No change," to which Blue replies that Bruce should come to New York and get more date contamination levels, exposure rates, types and amounts of radiation, the works. He glances at a photo of Betty he keeps before regretfully saying that he can't do that either and powers down for the night.
Meanwhile, at the Pentagon, Ross is receiving a report from his chief assistant, Major Kathleen Sparr (Christina Cabot) that an old man in Ohio died after he received gamma poisoning from his fruit drink that came from Brazil (note the man is Stan Lee, Marvel creator).
Ross quickly orders a team down there the next day, put together with no small amount of efficiency by his old army friend General Joseph Greller (Peter Mensah). The team is headed up by the Russian-born but America-trained Emil Blonsky (Tim Roth). Ross informs them all that their target is a scientist who has stolen military secrets and that he will definitely be a fighter if cornered.
As they fly down to Brazil, Bruce gets a message from Blue saying that he may have success, but needs Bruce's blood to be sure, which Bruce reluctantly -- and carefully -- sends off to him. That night, Bruce is sleeping soundly when Rick starts barking.
Meanwhile, the commandos have taken up position outside and are scanning the room with a camera, which Rick promptly eats (or tries to). Disgusted, the commandos blow off the door and after tranqing the dog, fire a dozen tranquilizers at a sleeping Banner. They whip the covers off and see that it's just pillows.
They hit the street after finding a rope, getting a little ahead of Bruce, who is hiding in the apartment of Martina just below him. After giving them a few minutes, Bruce hits the ground but is immediately spotted by Blonsky.
He breaks for it, going across rooftops and up the sides of buildings, at one point narrowly missing running right into a too-shocked-to-move Ross's arms. As he's running, he manages to crash into some people that turn out to be the gang from the factory.
They join in on the chase, and Bruce ducks into the factory to lose them all, but unfortunately the gang sees the chain swinging and the troops see the gang. The gang catches up with Bruce and start pummeling him, ripping off his backpack and tossing it aside as he begs them to stop before his heart-rate gets too high, getting out in Portuguese, "Me . . . angry . . . very bad."
The leader laughs and moves in for the kill while the troops near the fight, but suddenly Banner's eyes flash green just as a dart hits one of the toughs. They blame Bruce and start in again, but suddenly the leader is thrown a hundred feet through walls and the other men are screaming.
The troops can't make out what's happening, but Ross hears the audio feed and begins yelling at them to shoot, go live, do something! They switch to live rounds as the last of the gangers is finished and the creature turns to leave, smashing his way out with a big vat of something. The troops open fire, but the bullets just bounce off of him like plastic.
The creature roars and starts in on them as Blonsky tries to get in a higher position for a better view and shot. He finds it just as the last soldier is finished. He takes his shot, and the creature notices him. A shadow passes, and suddenly Blonsky is face-to-face with the Hulk. Hulk picks up another vat and heaves it at Blonsky, who goes flying as Hulk heads for the jungle, pausing only to give a victory roar.
Hours later, Ross and Sparr are going through Banner's apartment and computer when Blonsky comes in, demanding an explanation for what he saw out there.
Ross just says that he did a good job, and he should tell his men to pack up, since they're leaving town
1 DAY WITHOUT INCIDENT
Bruce wakes up beside a waterfall, not quite sure where he is, his pants hanging off of him and torn. He hears a truck and heads for the road, where the driver tells him he's in Guatemala. The driver takes Bruce into town, where Bruce proceeds to work his way north and pick up some new clothing while in Mexico.
Later, Blonsky has finally succeeded in wearing down Ross enough to tell him what went on. Ross explains that back in World War II, there were a lot of special programs being worked on to give America the edge, almost all of them under an Infantry Weapons Development program. One of them was a program for bio-tech force enhancment, more commonly known as "Super Soldier".
About five years ago, Ross dusted off that program and began trying to put it together again. He recruited Banner and his team to work on it, but then something went very wrong . . . or very right, depending on how you look at it. In either case, the end result, according to Ross, is that Bruce Banner's whole body is now, in his opinion, the exclusive property of the U.S. Government.
The two men sit there and after an exchange about how they're both fighters, Blonsky says that if he could put what he knows now in his body twenty years ago, that would be someone he wouldn't want to fight. Ross smiles grimly and says, "I could probably arrange something like that." Blonsky merely stares up at him, intrigued.
17 DAYS WITHOUT INCIDENT
At Culver University in Virginia, we see Bruce heading for the old science department where Hulk was born. However, the appearance of security guards checking IDs puts the kibosh on those plans. Deterred, he heads outside and sees the building housing all science teachers, and who should come out but Betty, chatting amiably with a friend of hers.
He stares at her stupidly as she eats outside, and she looks up towards him and smiles. He ducks behind a tree (yeah, that'll work), but she was actually smiling at her newly arrived boyfriend, Leonard Samson (Ty Burrel), psychologist extraordinaire. Now deterred and defeated, he heads to an old on-campus pizza parlor where the owner, Stanley (Paul Soles), is an old friend of his.
Bruce asks about Samson, and then asks for two more things -- a place to stay for a few days, and a job. The very next day we see him delivering pizzas in his old uniform, and one of the stops happens to be the science lab.
He talks to the guard (Lou Ferrigno, Hulk from the TV series) and is able to get upstairs, where after bribing the head computer genius with a pizza he gets on one of the computers to look for the data on his experiment, but it's all gone. Bruce contacts Blue and tells him the bad news, and then gets out of there.
That night, Bruce is getting ready to leave and Stanley is getting ready to close up when two final customers come in . . . Betty and Samson. They begin chatting with Stanley as an unaware Bruce comes down the stairs.
Just as Stan consents to make them a pizza Bruce opens the kitchen door and sees Betty, who sees him. Her mouth opens in shock, but when she looks again Bruce has taken off. She runs outside but doesn't see him hiding behind the dumpster, and once back inside she bullies Stanley into spilling the truth.
A while later, we see Bruce walking in the rain on a highway when Betty pulls up behind him. He sees her and she runs to him, begging him not to go.
Soon they are pulling into the house she shares with Samson, and she reveals a present she kept for him -- all the data from their experiment on a portable thumb drive. He tells her that he can't stay, but accepts her offer of money and a ride to the bus station the next morning.