Luke McNamara (Joshua Jackson) is a student with aspirations to become a lawyer. A “townie” who grew up on the “wrong side of the tracks”, he did well enough in school to attend college on a scholarship where he is a champion rower. His best friends at college are his love interest Chloe (Leslie Bibb), and Will (Hill Harper). Will is the coxswain of the Bulldog 8’s rowing team and Luke is the captain. At the victory party for the 8’s, Chloe is revealed to come from a wealthy family, and this is why Luke is reluctant to reveal his feelings for her. Luke’s friendships become strained when he is invited to join a secret society known as “The Skulls”. Luke passes the first part of the initiation process by stealing an artifact from a rival secret society. He does this with boxing prodigy Caleb Mandrake (Paul Walker) who The Skulls declare his co-conspirator and “soulmate”. Luke and Caleb are then lectured in the secret ritual room by a senior Skull who is standing in front of a wall with the word “WAR” engraved into it in huge capital letters. A senior Skull explains that the Skulls require their members to prove themselves in war. Luke has a falling out with Will when Will realizes that Luke has become a Skull.

Luke quickly strikes up a friendship with Caleb’s father, Litten Mandrake (Craig T. Nelson). Litten is the current Chairman of the Skulls and a Federal Court Judge who is pushing for a position in the Supreme Court. Litten and his partner Senator Ames Levritt (William Petersen) take an interest in Luke. Will, who has been conducting research on the Skulls for some time, discovers their secret ritual room. Will gets caught in the room by Caleb and in the ensuing struggle he falls and is knocked unconscious. Caleb is ordered to leave the room by his father, who then orders Skulls member and the University’s provost Martin Lombard (Christopher McDonald) to break Will’s neck. The Skulls manage to move the body and make it look like Will committed suicide in his dorm room by hanging himself.

Luke is greatly troubled by the death of his best friend. Luke’s parents supposedly died when he was young, and Will’s family is the only family he had. Stricken with grief, Luke begins to suspect Will was in fact murdered by Caleb. Caleb also believes that he is guilty, suspecting Will died as a direct consequence of Caleb hitting him. Luke enlists his ‘townie’ friends from childhood to help solve the mystery. His friends are first unwilling to work with him, as he missed one of their birthday parties, so as an apology and a bribe he gives them a 1963 Ford Thunderbird. With their help, Luke obtains the Skulls security tapes that prove Lombard committed the murder. In trying to convince Caleb of the truth (that his father was responsible for Will’s death), Luke realizes how scared Caleb is of his father. Before Luke can show the evidence to police, the Skulls council, who know Luke has stolen the tapes, vote that he is no longer loyal. Ames Levritt is blackmailed into voting against Luke by Litten Mandrake, who has pictures of him with his much younger mistress. When Luke does go to the police, the tape is switched by Detective Sparrow (Steve Harris) and Luke is confined to a mental hospital under the control of the Skulls.

With the help of Ames and Chloe, Luke manages to escape the hospital and he and Chloe survive an attempt on his life by Martin Lombard, who is shot and killed by Detective Sparrow (who it turns out is working for Levritt). Luke decides that his only option is to fight the Skulls by their own rules, and “bring war to them”. He challenges Caleb to a duel at the Skulls’ private island, by invoking rule 119. Litten tries to take his son’s place in the duel but is denied the opportunity due to another Skull rule. After Luke and Caleb take their ten paces and turn around, Luke drops his gun and tries to convince Caleb of the truth and that he is not responsible for Will’s murder. Despite being pressured by Litten to kill Luke, Caleb cannot bring himself to pull the trigger. At this point, Litten grabs a pistol and attempts to shoot Luke himself, but before he can fire, Caleb shoots his own father. Caleb, mortified at what he has done, tries to kill himself but is stopped by Luke.

The film ends with Luke’s realization that Senator Levritt manipulated Luke and others to bring about Litten’s death. Luke becomes disgusted with The Skulls and refuses to participate further, despite threats from Levritt that he will be tracked down someday, and despite, or even because of, Levritt’s offer that The Skulls will accept him because he has proven himself in war. As Luke walks away Levritt says to himself, “Well done son, well done”. This may be a hint that Leveritt is Luke’s biological father.

The final shot of the film shows Luke reuniting with Chloe.