Mike (Matt Damon) is a second-year law student, but he lost all his savings in a gambling game with casino owner Teddy (John Malkovich). Under the persuasion of his friend Kneesh (John Turturro), Mike vowed never to gamble again. However, he still showed his skills in the professor's card game, which shocked everyone. When picking up his old friend Worm (Edward Norton) from prison, Mike broke his oath and returned to the arena. In order to help Worm, he even delayed his internship in moot court. After that, his girlfriend Joe found evidence of Mike's involvement in gambling and broke up with him, which made him very depressed. Mike participated in gambling games one after another at the instigation of Worm. Afterwards, he found that he was tricked by Worm and owed a huge sum of money. He found Worm, who was forced to reveal the truth: it turned out that Worm was cornered by the fierce creditors. For the sake of friendship, he accepted the creditor's harsh conditions, but fell into an even more difficult predicament...