Breanna is throwing a house warming party at her recently renovated house, which has been outfitted with the latest in security systems, making the house impenetrable. As the guests begin to party, they discover that the house was the site of a horrific murder by a killer, known as the Knock Knock Killer, duly named for his use of stale knock-knock jokes. After conducting a séance to bring forth the ghosts of victims past, they unknowingly awaken the ghost of the killer, who was also killed in the house. As the party goers begin to be killed, they believe that it's the Knock Knock Killer, but...there's another killer.