When Shenna Preston, a young American movie star, abandons her film career and moves to London to study at art school, she anticipates a year full of nothing more eventful than painting. But tranquility turns to uncompromosing terror when a disturbed fan begins to haunt her life, and Shenna realizes that one of her acquaintances - indeed perhaps one of her closest friends - is a homicidal maniac, who will stop at nothing to possess her completely.