A loving father finds a clown suit for his son's birthday party, only to realize the suit is part of an evil curse that turns its wearer into a killer.
George Manning is a well-to-do businessman, husband, and father. While his family is away on his birthday, he invites a pair of rain-soaked young women into his house to wait out an evening thunderstorm. The two girls seduce Manning and ultimately kidnap and torture him in his own home.
After witnessing a mysterious woman brutally slay a homemaker, prostitute Liz Blake finds herself trapped in a dangerous situation. While the police thinks she is the murderer, the real killer is intent on silencing her only witness.
When his car breaks down, a quiet loner agrees to clean an abandoned family fun center in exchange for repairs. He soon finds himself waging war against possessed animatronic mascots while trapped inside Willy's Wonderland.