Bloch’s spine-chilling horror story opens in Phoenix where a young secretary, Marion Crane, absconds with $40,000 belonging to one of her employer’s customers. She heads for her boyfriend’s hometown of Fairvale with the intention of settling his financial problems so that they can marry. After a night’s driving she pulls in at the side of the road for a rest and is awoken next morning by a highway patrolman tapping on the window. Although they know nothing of the robbery the encounter unnerves her and she trades in her car before setting off again.
As the weather worsens she takes a wrong turning and finds herself outside a run-down motel where she decides to stay for the night. A young man, Norman Bates, runs the establishment and after checking her in offers to make her a sandwich as the nearest diner is several miles away. Over the snack they chat and Norman reveals the sad story of his life with his invalid mother who seems very domineering. Norman’s mood swings back and forward as they talk suggesting that all is not well at the Bates Motel.
Something Norman mentions strikes a chord with Marion and she decides to return to Phoenix to face the music but later that evening, as she relaxes in the shower, Norman’s mother, with the aid of a large knife, changes all her plans forever. A short time later, Norman discovers the crime and, like a dutiful son, clears away all traces of the horrific crime. Marion’s body and suitcase are stuffed in the boot of her car along with the hidden $40,000 and the car is then consigned to the swamp, which lies a short distance from the motel.
Guessing that Marion was heading for Fairvale, a private detective hired to retrieve the money, tracks down the boyfriend, Sam Loomis.
Marion’s sister is already there and having satisfied himself they know nothing he sets off to check the hotels in the area. Eventually he turns up at the Bates Motel and finds out that Marion stayed there. Not entirely satisfied with Norman’s answers he reluctantly leaves and checks back with Loomis and Marion’s sister telling them he is going back to the motel to question Norman’s mother.
His meeting with Mrs. Bates runs along very similar lines to that of Marion’s and Norman, ever the loving son, once again pays a visit to the swamp. Worried by his non-return, Loomis and Marion’s sister pay a visit to the local deputy sheriff and pour out the whole story. He also thinks something is very wrong but not for the same reasons. Mrs Bates, he assures them, has been dead and buried for the last ten years. Determined to uncover the truth the pair decide to pay a visit to the motel themselves.
Norman checks them in and while Loomis keeps him talking Marion’s sister slips off to the house to find the elusive Mrs. Bates. Realising that she is missing, Norman overpowers Loomis and rushes to the house in pursuit. Loomis follows after a few minutes and is just in time to save her from following in the footsteps of Marion and the detective. It is only then that Norman’s terrifying secret is finally revealed.