Marion Crane is a Phoenix, Arizona working girl fed up with having to sneak away during lunch breaks to meet her lover, Sam Loomis, who cannot get married because most of his money goes towards alimony.

One Friday, Marion's employer asks her to take $400,000 in cash to a local bank for deposit. Desperate to make a change in her life, she impulsively leaves town with the money, determined to start a new life with Sam in California.

As night falls and a torrential rain obscures the road ahead of her, Marion turns off the main highway. Exhausted from the long drive and the stress of her criminal act, she decides to spend the night at the desolate Bates Motel. The motel is run by Norman Bates, a peculiar young man dominated by his invalid mother.

After Norman fixes her a light dinner, Marion goes back to her room for a shower....