An ambitious Westport High School senior, Matthew Kidman (Emile Hirsch), dreams of a career in politics. He plans to attend Georgetown University if he can get a big upcoming scholarship. He begins a relationship with his beautiful new neighbor Danielle (Elisha Cuthbert), but soon discovers through his porn-addicted friend Eli (Chris Marquette) that she used to be an adult film actress known by her fans as \\\\\\\"Athena\\\\\\\".
Following Eli\\\\\\\'s poor advice, Matthew takes Danielle to a sleazy motel. Danielle guesses that Matthew has discovered her past and punishes him by performing a humiliating striptease and offering herself to him sexually. When Matthew becomes distressed, Danielle calls him on wanting to \\\\\\\"fuck a porn star in a cheap motel room\\\\\\\" and abruptly ends the relationship. When he attempts to reconcile with her later, he learns that she is leaving for Las Vegas with her ex-boyfriend, porn producer Kelly (Timothy Olyphant).
Matthew and his friends follow Danielle and find her performing at an adult film convention where Kelly menacingly warns Matthew not to interfere with his business. When Matthew convinces Danielle not to rejoin the industry, Kelly abducts Matthew from school and physically assaults him, saying that Danielle\\\\\\\'s failure to arrive on set has cost him $30,000. Kelly offers to let him erase his debt by breaking into rival producer Hugo Posh\\\\\\\'s home to steal an award statuette, but after Matthew has entered the house Kelly calls in a robbery report and leaves the premises. Matthew narrowly avoids the police and rushes to his scholarship dinner. High on ecstasy that Kelly told him was aspirin, he improvises a deeply sentimental speech but loses the scholarship due to his outrageous behavior.
Kelly then gets his money back by withdrawing $25,000 from an account Matthew opened to bring Samnang, a brilliant Cambodian student, to study in the United States (not wanting to explain his connections to the adult film industry, Matthew had previously introduced Kelly to the bank staff as his student adviser). Fearing that he will face expulsion or criminal charges for his unwitting role in the fraud, he turns to Danielle for help. Danielle calls in a few friends from her days as a porn star, and they agree to make a video for Hugo Posh on prom night and on school grounds. After the successful shoot, and after Eli has been dropped off with the tape\\\\\\\'s master copy, Danielle and Matthew make love for the first time in their limousine.
The next morning Matthew is shocked to discover Kelly, in possession of the tape he has stolen from Eli\\\\\\\'s home, with his parents and school principal at the dining room table. Kelly asks to speak privately with Matthew, then tells him that unless he is given half of all profits he will play the tape immediately. Matthew refuses because the money rightfully belongs to Samnang. Kelly repeats his threat, and Matthew, following Danielle\\\\\\\'s advice to \\\\\\\"just go with it\\\\\\\", says that he no longer cares about his now-ruined future. As the tape begins to play, it becomes clear that Matthew and his friends have made a progressive, comprehensive sex ed tape rather than a pornographic film. With no more cards left to play, Kelly, completely humiliated, finally admits defeat.
In the film\\\\\\\'s closing montage, we learn the fates of the film\\\\\\\'s central characters, including Kelly, Eli, and Matthew\\\\\\\'s friend Klitz. Hugo Posh and Matthew make millions from the video, although Matthew serves as Posh\\\\\\\'s \\\\\\\"silent partner\\\\\\\" and his involvement is largely kept secret. Posh keeps his word and pays for Samnang to come to the USA, while Matthew has enough money to attend Georgetown and take Danielle to DC with him. Matthew\\\\\\\'s story ends with him getting the girl of his dreams and a chance at the future he has always wanted.