A female aerobic instructor is possessed by an evil spirit of a fallen ninja when coming to his aid. The spirit seeks revenge on those who killed him and uses the female instructor’s body to carry out his mission. The only way the spirit will leave aerobic instructor’s body is with the help of another ninja.

Phillip Filmore is a naive, 15-year-old, preoccupied with sex, who develops a crush on Nicole Mallow, the new 30-something, French housekeeper and sitter to look after him when Phillip’s father is out of town for the summer on a “business” trip. But Mr. Filmore’s unscrupulous chauffeur, Lester Lewis, takes advantage of Phillip’s crush on Nicole to hire her to seduce the youth, then draws her into a plot to fake her own death in a blackmail scheme aimed to drain Phillip’s trust fund.