Director Tod Browning created the eerie mood of vampires roaming around at night. For the surprise ending, see (or don't see) below.
Dr. J. Doskil (Donald Meek) arrives at an inn and laughs at vampires. Baron Otto von Zinden (Jean Hersholt) announces to the employees the murder of their master, Karell Borotyn. The doctor finds the mark of the vampire, but Inspector Neumann (Lionel Atwill) demands to know the real cause of death. He suspects heiress Irena Borotyn (Elizabeth Allan) and the executor of her estate, Baron Otto. Dr. Doskil says the body was drained of its blood. Fedor Vincenty (Henry Wadsworth) staggers in, saying he woke up by the castle. Irena sees vampire wounds in his neck. Count Mora (Bela Lugosi) watches his entranced daughter Luna (Carroll Borland). A terrified couple sees her on their way home. Luna swoops over Irena. Later Irena says she fainted. Professor Zelen (Lionel Barrymore) agrees with the doctor's diagnosis, and he tells the Inspector he will use the herb bat-thorn. He tells Irena to stay inside at night.
Otto and Neumann check Borotyn's grave and find the coffin empty. The professor tells Fedor to leave, because being an earth-bound vampire is worse than death. The maid sees a bat and then Count Mora in the house. The professor has the house searched, and he sees the late Borotyn (Holmes Herbert) with Mora. Borotyn plays the organ. The professor tells Neumann and Otto that they must destroy the vampires during the daylight. Irena describes what happened to her, and the professor says that she is in their power. Neumann shoots at a bat; but it does no good at night. They find Borotyn, and the candle goes out. Irena tells Fedor to go. She opens the doors and acts gaily. The professor and Otto look for the Inspector. Borotyn tells Irena to go with Luna. Fedor comes in as Luna is bending over Irena's neck. The professor hypnotizes Otto to go upstairs. Irena tells Neumann that she will not act with the man playing her father but is persuaded by the professor so that Otto will re-enact his crime. Otto puts a drug in Borotyn's glass. The professor has him drink it and collapse. Otto sees and prepares to cut into his neck when the professor comes and brings Otto out of his trance, arresting him for murdering Borotyn in order to win over Irena. Mora, Luna, and others remove their make-up after this acting job.
Horror fans are often disappointed by this ending that spoofs the basis of the terror created. Yet from realistic and dramatic perspectives it effectively shows how a drama can create such a strange mood out of people's fears.