Psychology student Scott and his friends Joe and Suzie are attending university in Brighton. Scott comes in contact with Rich Bitch via chatroom. When they meet in person, she's a fellow student named Charlie who seduces and beds him before vanishing.

The flatmates begin playing the computer game Killer Net. Scott plans the perfect murder and chooses Charlie as his victim. When she's found murdered, Scott is arrested and he learns the game's methods mirror real life.

Scott attempts to recreate Killer Net but Charlie is no longer in the game. PC Pam Boxer offers to be the victim, unaware that someone is watching. Things become sinister when the police receive a threatening email from a user named Dome.

With Scott on remand for Charlie's murder, the police try to build evidence against him, but at least one officer believes he's innocent. When Joe's girlfriend catches Joe in a lie, she starts to suspect him.