19th Century England. Sir James Forbes receives a rambling letter from Peter Thompson, a former student, about a mysterious plague that has been afflicting the village where he is now the general practitioner.

Sir James sets off for Cornwall accompanied by his daughter Sylvia, who is a childhood friend of Thompson's wife, Alice. They arrive at the village, where a funeral is taking place for the latest victim of the plague. A group of huntsmen, who Sylvia angered earlier, overturn the coffin and spill the corpse into the road.

Sir James and Sylvia arrive at the Thompson residence and are greeted by Alice, who seems pale and dazed. Sylvia stays with her while Sir James sets off to find her husband.

Peter Thompson is in the pub. Sir James interrupts an argument between Peter and Martinus, the brother of the latest plague victim. Calming the situation with a round of drinks, Sir James learns that Squire Hamilton has not allowed any autopsies to be carried out on the victims of the plague.

That night Sir James and Peter go to the cemetery to disinter Martinus's brother so they can carry out a proper examination. The local police sergeant apprehends them just as they learn that the coffin is empty. Initially threatening to arrest them for body snatching, the sergeant soon changes his mind when he sees what they have found.

Meanwhile, Alice has slipped into a hypnotic trance. Following the sound of drums, she heads off towards an abandoned tin mine just outside the village. Sylvia follows, but soon loses her way in the woods. The huntsmen surround her, and then drag her off to Hamilton's mansion.

At the mansion, the men cut cards to see who will rape her first. Hamilton stops the lead huntsman from attacking Sylvia and apologises profusely to the shaken woman. Refusing the offer of a ride home in the Squire's carriage, Sylvia begins to walk. She comes upon the tin mine, where she sees a zombie hurl Alice's lifeless body from the pithead.

Sir James, Peter and the sergeant set out to search for Alice. They find her body in the woods near Martinus, who is sleeping off the previous night's drink. The sergeant locks him away, whilst Sir James and Peter carry out an autopsy on Alice. They discover that her body is not suffering from rigor mortis, and that animal blood has been smeared on her face. Squire Hamilton pays a visit to the Thompson residence on the pretext of offering his condolences. Discovering that Sylvia is in the house alone, he engineers an accident where she cuts her hand, and then steals a few drops of blood.

During Alice's funeral, Sylvia becomes weak and nearly faints. Hamilton has smeared a voodoo doll with her blood and placed it with a large collection of similar effigies in his study.

Sir James, Peter and the elderly local vicar keep a midnight vigil over Alice's grave. Distracted from their task by an assault on the old man, Sir James and Peter return to discover that Alice has risen from the dead. Sir James beheads her with a spade.

Peter has a vivid nightmare in which dozens of zombies claw their way out of the ground. Upon waking, he and Sir James decide to check the graves of the other plague victims, and find them all empty. Meanwhile, Martinus vanishes from his jail cell after a visit from Hamilton; the circumstances are similar to those surrounding Alice's disappearance and death.

Sir James confronts Hamilton and accuses him of using witchcraft. The Squire's only response is to have him thrown out of his house. He sneaks back in and discovers the large collection of voodoo dolls, but is attacked by the lead huntsman. During the struggle, the huntsman is killed and the house catches fire.

The newly resurrected Martinus takes Sylvia to the tin mine, where the Squire plans to enslave her. All the plague victims are working in the mine, turned into zombie slaves by Hamilton's black magic.

Peter rescues her before the ceremony is completed, just as the house fire burns the Squire's collection of dolls. The zombies kill the Squire and his men, before exploding into flames. Sir James, Peter and Sylvia are reunited as they watch the tin mine destroyed.