Hayley Stark is fourteen years old and is chatting online with Jeff Kohlver, a thirty two year old photographer who has no business engaging in a sexually explicit flirtation with a minor. The two agree to meet at a coffee shop, and afterwards, Jeff takes Haley home with him. Hayley fixes them drinks and makes screwdrivers, going heavy on the vodka and not so heavy on the orange juice. Hayley flirts with Jeff some more and asks him to take her picture, but he cannot, because he is starting to feel dizzy. His vision blurrs a little and he suddenly collapses, unconscious.
He wakes up to find that he is tightly tied to a chair, with Hayley standing before him. She tells Jeff that she has been tracking him because she knows he is a pedophile. She met him in the coffee house with the intention of drugging him and punishing him for being a rapist and a murderer, and getting away with it. Jeff, predictably, denies the accusations and tells Hayley that she does not understand, his intentions were always good. She looks around the house and finds a gun and a locked safe, which contains sexualized images of children, and a picture of a girl Hayley recognizes as Donna Mauer, a local teen who has been kidnapped. She is still missing. Jeff denies knowing anything about her disappearance. Still tied to the chair, he realizes that he can reach his gun, and goes to attack Hayley but she puts plastic wrap around his face, and he is rendered unconscious again.
Waking again, he sees that Hayley has taken further precautionary measures to protect herself from him. He is bound to a steel table and there is a bag of ice on his genitals. Hayley is going to castrate him. Jeff still thinks he can worm his way out of his predicament; he alternately sweet-talks and begs but Hayley does not fall for his manipulation. He then tells her that he cannot help what he is because he was sexually abused when he was a child, and would therefore never do anything to hurt others.
He cannot feel the castration because the bag of ice has numbed all feeling. Afterwards, Hayley goes upstairs to take a shower, and Jeff frees himself from the table. He realizes that Hayley did not castrate him at all, but faked it to play with his mind. He goes into the bathroom and tries to attack her as she is in the shower, but she has anticipated this and attacks him from behind with a stun gun.
Awakening again, he finds himself with his hands bound behind him and a noose around his neck. He is standing on a chair that it seems Hayley is going to kick away at the right moment. She calls his ex-girlfriend, Janelle, and posing as a police officer, asks her to come to the house as soon as she can.
Leaving him momentarily to answer the front door to a girl scout selling cookies, Hayley returns to the kitchen to find that Jeff has again managed to free himself. He chases he and catches up with her on the roof, as Hayley planned that he would. She has brought the noose with her from the kitchen and has secured it around the chimney. She keeps the gun pointed at Jeff to keep him away from her.
Jeff confesses at last, still trying to save his own skin. He tells Janelle that he watched another man kill Donna Mauer after raping her. If Hayley allows him to live he will tell her the name of the other man. Hayley has a revelation of her own; she already knows the name of the other man. Aaron, she tells him. told her Jeff's name just before he killed himself. As they see Janelle arrive at the house, Hayley urges him once more to kill himself, promising to destroy the evidence in return. Jeff gives in. He allows Hayley to put the noose around his neck. He jumps from the roof, after which Hayley mutters, "or not" under her breath. Without hiding the evidence, she hastily escapes through the woods, wearing a bright red hoodie.
