Bruno Antony thinks he has the perfect plot to rid himself of his hated father and when he meets tennis pro Guy Haines on a train he thinks he's found the partner he needs to pull it off. His plan is relatively simple. Two strangers each agree to kill someone the other person wants disposed of. For example, Guy could kill his father and he could get rid of Guy's wife Miriam, freeing him to marry Anne Morton, the beautiful daughter of a U.S. Senator. Guy dismisses it all out of hand but but Bruno goes ahead with his half of the 'bargain' and disposes of Miriam. When Guy balks, Bruno makes it quite clear that he will plant evidence to implicate Guy in her murder if he doesn't get rid of his father. Guy had also made some unfortunate statements about Miriam after she had refused him a divorce. It all leads the police to believe Guy is responsible for the murder, forcing him to deal with Bruno's mad ravings.

Phoenix officeworker Marion Crane is fed up with the way life has treated her. She has to meet her lover Sam in lunch breaks and they cannot get married because Sam has to give most of his money away in alimony. One Friday Marion is trusted to bank $40,000 by her employer. Seeing the opportunity to take the money and start a new life, Marion leaves town and heads towards Sam's California store. Tired after the long drive and caught in a storm, she gets off the main highway and pulls into The Bates Motel. The motel is managed by a quiet young man called Norman who seems to be dominated by his mother.