Psychopathic serial killer Christopher Gill (Rod Steiger) is obsessed with his late mother, and he targets victims who remind him of her. He dons various disguises to gain his victims' trust and always leaves his calling card, a red lipstick mark, when he's done. Christopher begins deliberately tipping off detective Morris Brummel (George Segal) on the phone, drawing the detective -- who has issues with his own overbearing mother (Eileen Heckart) -- into a game of cat and mouse.