
15 plot points

Phoenix hotel room. Marion Crane and lover Sam Loomis after lunchtime affair. He cannot marry, financially struggling. She wants marriage. Trapped in dead-end relationship. Respectable woman, unfulfilled. Desire for different life.
Marion to Sam: "I am tired of sneaking around." Theme of traps - financial, emotional, psychological. Everyone trapped. Some traps we choose, some are imposed, some are inescapable.
Marion returns to real estate office. Boss trusts her to deposit $40,000 cash. Temptation. She is honest, reliable secretary. Sam needs money. This could solve everything. One choice could change everything.
Marion steals money. Packs, drives to California with cash. Sees boss at intersection, he sees her. Panic. Point of no return. Respectable woman becomes criminal. Old life over. Running now. Can never go back.
Driving through rain. Paranoid. Cop follows her. Trades cars. Should she continue or return money? Every interaction feels suspicious. Rationalizing. Money within reach but guilt eating her. Storm worsening. Getting lost.
Stops at Bates Motel in storm. Norman Bates, awkward proprietor, lives with invalid mother in house behind motel. Lonely, kind. Marion decides to return money tomorrow. New resolve. But trapped at motel tonight.
Norman and Marion talk. He speaks of traps: "We are all in our private traps." Mother calls him, demanding. Marion sympathizes. He is trapped too. Connection forming. She sees her own situation reflected. Both trapped differently.
SHOWER SCENE. Marion killed by mother. Brutal, shocking murder. Protagonist dead 47 minutes in. Subversion of every expectation. Norman finds body, cleans scene, sinks car with money in swamp. Genre shifts from thriller to horror.
Marion sister Lila and Sam search for Marion. Detective Arbogast investigates. Finds Bates Motel. Questions Norman about Marion. Norman nervous. Investigation beginning. False hope: they might find her. But she is dead. Stakes shifted entirely.
Arbogast goes to Bates house. Mother kills him. Norman hides body. Lila and Sam suspicious. Go to motel. Norman acting strange. They know something is wrong but not what. Killer still active. More danger.
Sam distracts Norman. Lila explores house alone. Norman knocks out Sam, runs to house. Lila trapped. Descends to basement. Desperate. Norman coming. Mother in basement. Confrontation inevitable. Terror peak.
Lila finds mother - mummified corpse. Norman enters dressed as mother with knife raised. About to kill. Sam arrives, stops him. Norman caught. Truth revealed: Norman killed mother years ago, became her. Psychotic break. Mother lives through him.
Psychiatrist explains: Norman has split personality. Mother personality dominated. Norman ceased to exist. Killed anyone mother was jealous of. Marion triggered it. Understanding the horror. Synthesis: ultimate trap is one you build inside your mind.
Norman in cell. Mother personality fully taken over. "She would not hurt a fly." Norman completely gone. Insanity total. Marion car pulled from swamp. Money means nothing now. Justice hollow. Horror of fractured mind.
Norman/mother smiling. "They are probably watching me. Let them see what kind of person I am." Skull superimposed on face. Mother is all that remains. Norman dead inside. Most terrifying trap: the inescapable one. Chilling.