Brian Spillner spends three weeks coming to a diner owned by Dom Toretto, leader of the hottest drag racing gang in the city along with his girlfriend Letti, trying to get in his good graces. He also starts flirting with Dom’s sister Mia, gaining the enmity of Dom’s crew member Vince who’s also interested in her. They get in a fight which gets Dom to ban Brian from the diner, and even try to get him fired from his mechanic job, with the same company who works on the gang’s cars.
Brian isn’t deterred and hooks up a nitrous oxide (nos) system to his car which will supercharge the engine, and enters the next race with his car as collateral. With the nos’ help he nearly catches Dom, but the speed ends up overstressing the car and wrecking its engine. The cops raid the race after it’s over, and when Dom is caught out of his car, Brian comes to his rescue. This finally gets Dom’s respect and they share that they’ve both done prison time for stealing cars, with Dom swearing he’ll die before going back.
The police chase takes them into the territory of Chinese gangster Johnny Tran, who hates Dom after a deal gone bad. Johnny and his cousin Lance destroy the car before Dom can take possession, and after taking a cab home, Dom is outraged to see the gang has been having a party while he was missing, which gets him to invite Brian in, though Brian is also still in debt for the car.
The next day, Brian is pulled over and arrested, which is revealed to be a front for anyone watching, as he’s actually Brian O’Conner, a cop working undercover to catch street racers who are robbing electronics in transit with three Honda Civics. FBI supervisor Bilkins is losing patience and insists Dom be arrested as the top suspect, but Brian asks to have a few more days to get hard evidence.
The race MC Hector orders parts matching the Civics, and Brian breaks into his garage and finds the cars are indeed there. But Vince was following him, and takes him to Dom under suspicion of being a cop. Brian claims he was just scoping out the competition for the upcoming Race Wars in the desert so he could clear his debt, and together they also take a look at Johnny’s garage. Johnny comes back and they’re forced to hide, and witness him confronting his fence Ted over double-dealing on the new cars’ engines.
Bilkins now wants to bring Ted in as a witness, but Brian still insists he can get better evidence. He also doubts Dom is the thief as he’s too “controlled,” but his boss Tanner brings up an incident where Dom nearly beat a man to death with a wrench. Soon enough, Dom himself reveals the full story, that he was going to follow his father into legitimate racing until his father was killed when another driver bumped him during a race. Dom beat the man in a blind rage, which got him banned from the sport and sent him into his current life. He still keeps his father’s Charger in the garage, but has never worked up the courage to drive it himself.
The thieves hit another truck, and Brian is in bed with Mia when Tanner calls for confirmation to arrest Johnny, forcing him to agree to end the call quickly. After the arrest of Johnny’s whole gang, the FBI is forced to release them for lack of evidence, and Bilkins gives Brian just one more day to make his case, with Tanner encouraging him to accept it really is Dom. Brian implies to Dom that he knows about the heists and wants in, so Dom agrees to let him into Race Wars to see what he’s got.
At Race Wars, Dom’s man Jessie goes up against Johnny, having bet his father’s car. Johnny wins due to his own nos rig, and Jessie freaks out so much he simply keeps driving and abandons everyone. Johnny then accuses Dom of ratting him out to the cops, starting a fight between the gangs. This gets Dom desperate enough to pull one last heist, despite knowing the truck drivers are now much better prepared. To help him, Brian is forced to reveal to Mia that he’s a cop, and together they trace Dom’s cell phone and head off to save him.
The truck driver who Dom targets turns out to be armed with a shotgun, and Vince ends up trapped on the truck hood with the driver stopping any attempt to help him, including crashing Letty’s car. Finally Brian arrives and is able to get Vince out with some especially daring maneuvers, but he’s still badly injured and Brian has to reveal he’s a cop to everyone to get an ambulance in time.
Brian catches up with Dom at his house, and their confrontation is interrupted when Jessie arrives. Soon after, Johnny and Lance drive up and shoot at everyone, killing Jessie. Brian and Dom again put their differences to the side to get payback, Dom even driving his father’s Charger for the first time. After Johnny is killed and Lance injured and left to be arrested, Brian goes back after Dom, who challenges him to a race over a railroad track as a train approaches. Both of them barely make it, but then Dom crashes into a truck, leaving him injured and the Charger wrecked. As the other police start to arrive, Brian reminds Dom he owes a car, and hands over the keys to his own so Dom can escape, with Brian staying to face the consequences.
