Elliot, a successful gynecologist, works at the same practice as his identical twin, Beverly. Elliot is attracted to many of his patients and has affairs with them. When he inevitably loses interest, he will give the woman over to Beverly, the meeker of the two, without the woman knowing the difference. Beverly falls hard for one of the patients, Claire, but when she inadvertently deceives him, he slips into a state of madness.
A small, seemingly innocuous plastic reel of film leads surveillance specialist Tom Welles down an increasingly dark and frightening path. With the help of the streetwise Max, he relentlessly follows a bizarre trail of evidence to determine the fate of a complete stranger. As his work turns into obsession, he drifts farther and farther away from his wife, family and simple life as a small-town PI.