THE VAMPIRE BAT

When the villagers of Kleinschloss start dying of blood loss, the town fathers suspect a resurgence of vampirism, but police inspector Karl Brettschneider remains skeptical. Scientist Dr. Otto von Niemann, who cares for the victims, visits a patient who was attacked by a bat, Martha Mueller. Out of appreciation for her kindness, Martha is visited by a highly eccentric man named Hermann Gleib, who claims he likes bats because they are "soft like cat" and "nice".

On the doctor's journey home, he meets Kringen, one of the townsfolk, who claims to have been attacked by the vampire in the form of a bat, but withheld his story from the town in order to not spread fear. Dr. von Niemann encourages Kringen to tell the townsfolk of his story. Kringen becomes suspicious that Gleib may be the vampire due to his obsession with bats. Gleib lives with bats and collects them off the street.

Dr. von Niemann returns to his home, which also houses Brettschneider's love Ruth Bertin, Ruth's hypochondriac aunt Gussie Schnappmann, and servants Emil Borst and Georgiana. Fear of the vampire and suspicion of Gleib quickly spread around the town and people start fearing him. Ms. Mueller is killed that night. The analyses of Dr. von Niemann and another doctor, Dr. Haupt, conclude that the death is the same as all of the previous deaths – blood loss, with two punctures in the neck caused by needle-sharp teeth. Gleib enters the examination, and upon seeing the dead body, runs away screaming.

Next morning, Gleib enters Dr. von Niemann's garden, where Dr. von Niemann, Brettschneider and Bertin are discussing vampires inside the house. The town fathers enter the house and announce that Kringen is dead and Gleib is missing. An angry mob hunts down Gleib and chases him through the countryside and into a cave, where he jumps to his death.

That night, Dr. von Niemann is seen telepathically controlling Emil Borst, as he picks up sleeping Georgiana and takes her down to Dr. von Niemann's laboratory, where a strange organism is seen. They then drain her blood from her neck.

Schnappmann then discovers Georgiana's body in her bed. Dr. von Niemann and Brettschneider investigate and find Ms Mueller's crucifix, which Gleib handled the night Dr. von Niemann visited her. Brettschneider is becoming more convinced of the presence of vampires in the village as no other plausible explanations for the deaths can be found. As Gleib was seen in the garden that morning, the two conclude he is guilty.

Upon hearing of Gleib's death, however, Brettschneider's conviction is erased. Dr. von Niemann tells Brettschneider to go home and take sleeping pills, but gives him poison instead, intent on draining his blood. Bertin discovers Dr. von Niemann telepathically controlling Borst, who is at Brettschneider's house. It is revealed that Dr. von Niemann has created an artificial lifeform and is using the blood to feed his organism. He ties Bertin up and gags her in his lab. Borst supposedly enters with Brettschneider's body on a trolley. Dr. von Niemann walks over to Borst, who is revealed to be Brettschneider (who did not take the pills) in costume, with the real Borst on the trolley. Brettschneider pulls a gun on Dr. von Niemann and walks over to untie Bertin. Dr. von Niemann then wrestles Brettschneider, who drops the gun. Borst picks up the gun, points it at von Niemann and tells Brettschneider to finish untying Bertin and get her out. As the couple exit the room they hear two shots. Brettchneider goes back into the room to find them both dead.

Dr. von Niemann is revealed as the true culprit, using blood to feed an artificial organism. He is confronted and stopped before he can claim more victims.

The film subverts the villagers' superstitions by exposing the real threat as a mad scientist rather than a supernatural vampire. In the end, mob paranoia is shown to be misdirected, while science—rather than folklore—unmasks the true danger. This twist reflects the era's fascination with rational explanations behind seemingly supernatural events.