Karen McCann's eldest daughter is raped and murdered whilst on the phone with her. When the case against Robert Doob, the perpetrator, is dismissed because of a technicality, she starts following him and sees how he checks out his next victim, a woman he delivers groceries to. She tells the police, but is only warned she must stop following Doob. When she tries to warn the woman, she is shooed out of the house. Doob, having found out that Karen is following him, threatens to do something to her...