Two female students -- wealthy, popular Kelly Van Ryan (Denise Richards) and goth trailer dweller Suzie Toller (Neve Campbell) -- accuse Sam Lombardo (Matt Dillon), a high school guidance counselor, of rape. Before this, Sam gives Kelly a ride home, at which time they listen to both Third Eye Blind and Smash Mouth on a car stereo. During the trial, Suzie reveals that Sam did not rape her and that Kelly fabricated the charges because she was in love with him and angry that he slept with her mother. The trial humiliates Kelly and her entire family, and Sam receives a generous settlement ($8.5 million), which he uses to retire peacefully. It is then revealed that Sam, Kelly, and Suzie orchestrated the scandal with the aim of taking the money from the trial.
As police sergeant Ray Duquette (Kevin Bacon) becomes suspicious, Suzie becomes increasingly nervous and Sam worries that she will undermine their plan. After Kelly has an affair with Suzie, Sam and Kelly take her to the seaside, where Sam murders Suzie with a wine bottle. In the investigation into Suzie's disappearance, police find her blood and teeth by the ocean. Ray discovers Sam is the killer and goes to Kelly's house to protect Kelly from Sam. In the confrontation between Kelly and Ray, both are shot, Kelly fatally. Ray explains how she shot at him and he had to return fire. Ray is discharged from the police force following this incident, while Sam spends time at a tropical resort. Sam goes to his room and finds Ray there -- Ray and Sam had been collaborating the whole time.
They later go cruising in Sam's boat in the ocean, where Sam knocks Ray overboard. When Ray climbs back onboard, Suzie, alive and now with blonde hair, shoots him with a spear gun and Ray disappears into the surf. Before Ray falls over, he pleads to Sam for help. Sam would say "you should not have killed Kelly", signifying he and Suzie showed no remorse in having to kill Ray. As Sam relaxes, Suzie gives him a drink laced with poison and knocks him overboard. She sails the boat back to shore by herself.
A series of flashbacks explains the story. Suzie devised the plan, in which she wished to receive the money from the trial, as payback to her wealthy stepsister Sandra Van Ryan (Kelly's mother played by Theresa Russell) for being scorned and abandoned by their father. Suzie also wanted to kill Ray in revenge for killing her friend, Davie, some time ago (Davie tried to intervene to protect a prostitute that Ray was roughing up, so Ray killed him, then busted Suzie for drugs and sent her away to a correctional facility so she couldn't be a witness against him). She manipulated all the characters in the plot, making Sam seem the mastermind and faking her own death (she had photos of Sam and Kelly partaking in drugs and underage kinky sex to blackmail Sam into joining the plot). She was underestimated because of her delinquency and poor background. Those who knew her say her IQ was around 200 and, if she put her mind to it, "she could do anything." As for Kelly's death, Ray shot her first and then put a gun in her hand and made it appear that she had shot at him.