In London, the American futile housewife Katherine "Kit" Preston has been married for three months with the American executive Anthony "Tony" Preston. In a foggy day, while walking in a park, Kit is threatened by a voice that tells that she will be murdered by the end of the month. On the next day, Kit receives a phone call from the stalker and she goes with Tony to the Scotland Yard, but Inspector Byrnes believes that Kit is making-up the story to get more attention from Tony. Kit welcomes her Aunt Bea but only she receives the phone calls. Would Kit be losing her mind?