A man tells a story about a mad doctor who uses a somnambulist to murder people and discovers that the doctor is the director of an asylum.
Francis (Friedrich Feher) tells a companion that Jane (Lil Dagover) is his fiancée and then tells him about his town.
Francis urges his friend Alan (Hans Heinrich von Twardowski) to go to the fair. Dr. Caligari (Werner Krauss) uses a bribe to see the town clerk and asks for a permit to exhibit a somnambulist. Caligari goes to the fair and announces that people can see Cesare, a somnambulist.
That night the town clerk is murdered. Caligari says that Cesare has been asleep for all his 23 years. People go in the tent. Caligari opens his cabinet and tells Cesare (Conrad Veidt) to awake. Cesare opens his eyes. Alan and Francis watch. Caligari says that Cesare can answer questions. Alan asks how long he will live, and Cesare says until dawn.
Francis and Alan both love Jane and agree to remain friends. Alan wakes up, and he is stabbed. The landlady tells Francis that Alan is dead. Francis goes to the police. Grieving, he tells Jane. Dr. Olson (Rudolph Lettinger) tells Francis that he will question Cesare. Caligari feeds Cesare with a spoon. He lets Francis and Dr. Olson come in. Men take a suspected murderer to the police. Dr. Olson examines Cesare, but he is asleep. A newspaper says that the murderer was caught. The suspect admits he tried to kill an old woman, but he says he did not kill the others.
Jane looks for her father, Dr. Olson. Caligari invites her in and shows her Cesare; she runs out. As she sleeps, Cesare walks to her and grabs her. Cesare takes her away, and her relatives follow and retrieve her. Jane wakes up and tells Francis that it was Cesare. Frank tells the police he wants to see the prisoner. They go to Caligari and find a dummy in the cabinet.
Francis goes to an asylum and asks if Caligari is there. They take him to the director. While Caligari is asleep, they investigate in his office. In a book they read about the mystic Caligari and Cesare. They read his diary how Caligari found his Cesare, who could be driven to commit murder. He decides to become Caligari.
A man reports to Francis a sleeper is in the fields. Francis confronts Caligari and shows him Cesare. Caligari gets upset and has to be restrained in a straitjacket.
Francis tells his companion that since then the madman has not left his cell. In the asylum Francis tells him not to let Cesare predict your future. Francis asks Jane to marry, but she says she is a queen. Francis says the director is insane and attacks him. Francis is restrained, and the director says he knows how to cure him.
This pioneering expressionist drama reflects a murderous
demon in the subconscious that may be activated by someone with
hypnotic abilities. This early horror film could be seen as a
warning of what happened in Nazi Germany, where millions were
persuaded to murder millions of people.