Rod Steiger stars as Christopher Gill, a serial killer who is fixated on his late mother, who had been an actress. Gill preys on older women who remind him of her. A Broadway theater director and costumer, he adopts various disguises, e.g. priest, policeman, plumber, hairdresser, etc., to put his victims at ease (and also avoid being identified) before strangling them and painting a pair of lips on their foreheads with garish red lipstick.
Gill strikes up an adversarial relationship, via telephone, with Detective Morris Brummel (George Segal), who is investigating the murders. As Brummel realizes that the killer has access to costumes, he seeks out local costume outlets, and tracks down Gill. Once he sees a portrait of Gill's mother with bright red lipstick in the theater, he knows he has his man.
