Based on a story by Robert Louis Stevenson, a teaching medical doctor relies on a grave robber who turns to murder to sell corpses for dissection.
In 1831 Edinburgh, Mrs. Marsh (Rita Corday) brings her paralyzed daughter Georgina (Sharyn Moffett) to Dr. MacFarlane (Henry Daniell), who calls in his student Donald Fettes (Russell Wade) for his bedside manner. MacFarlane says a new operation could be done, but he teaches and cannot do it. Fettes wants to give up medicine, but MacFarlane makes him his assistant. At night John Gray (Boris Karloff) brings in a body; Fettes helps carry it in and pays Gray thirty pounds. Mrs. Marsh asks Fettes to help persuade MacFarlane. Fettes sees the woman whose son's body was stolen and wants to quit, but MacFarlane dissuades him. Gray gets MacFarlane and Fettes to drink with him. Fettes asks MacFarlane to operate on Georgina, and Gray also urges him. Fettes tells Georgina she will have to undergo pain. MacFarlane kisses Meg Camden (Edith Atwater) passionately. MacFarlane tells Fettes he cannot operate without studying specimens' spines. Fettes calls on Gray, and he gets another body. Fettes says it is a street singer who was just alive, and he tells MacFarlane that she was murdered; but MacFarlane says not to report it.
MacFarlane operates on Georgina as students watch. Fettes tells MacFarlane that she is healing, but she does not want to walk. Gray drinks with MacFarlane and criticizes him. Gray says he took the blame for MacFarlane in the trial. MacFarlane tells Gray to leave. MacFarlane's servant Joseph (Bela Lugosi) calls on Gray and asks for money or he will tell the police of his murders. Gray gives him money and brandy but then suffocates him, taking his body to MacFarlane's place. MacFarlane finds Gray drinking with Meg and tells him never to come back; but Gray tells him to look downstairs. MacFarlane and Fettes find Joseph's body. Meg tells Fettes that Gray is evil, and she urges Fettes to leave. MacFarlane goes to Gray and offers him a house to get rid of him. Gray says he likes having power over MacFarlane. They fight, and Gray refrains from killing him; but then MacFarlane kills Gray and takes the body, showing it to Meg. Fettes tells Mrs. Marsh and Georgina that he left MacFarlane. Georgina wants to see a horse and walks. Fettes goes to tell MacFarlane, who says Gray left. MacFarlane and Fettes go to a cemetery and dig up a body. In the rain MacFarlane thinks it is Gray, and the carriage goes down a hill. Fettes finds the bodies of MacFarlane and Meg.
This macabre story reflects the clumsy efforts of early
modern medicine to study cadavers in order to improve operations.
The doctor has taken advantage of the grave-robber but is controlled
by him even after his death.