A woman is tortured by the sudden disappearance of her only child years before. Obsessed with having another baby, she is devastated and driven to emotional crisis when discovering her new husband is infertile. Gripped by despair, the woman begins to resign herself to the bitter likelihood of never having another child. Striking up a friendship with two discarded young laborers hired to re-paint her son's now silent room, the three lost souls form a disturbing bond as the boys are led deeper into the woman's tormented world. Her family's suspicions of this unsettling new friendship sets off an irreversible series of events, leading to madness and murder as the horrors of the past collide with the sins of the present, ending in tragedy and terror.

Scottish archaeologist Angus Flint discovers an odd skull amid the ruins of a convent that he is excavating. Shortly thereafter, Lady Sylvia Marsh returns to Temple House, a nearby mansion, far earlier than expected. At a party in the village, Angus meets Lord James D'Ampton, who has just inherited his family's land right next to Temple House. Angus learns of the D'Ampton Worm, a huge dragon-snake that an earlier D'Ampton killed by cutting it in half. (There's a pretty catchy rock-folk song that tells the D'Ampton Worm legend.) As people begin disappearing and acting strangely over the next few days, the skull is stolen from Angus's room, and the watch of a missing person is found in a cavern that was the legendary home of the D'Ampton worm. Angus and James discover that there was an ancient cult that worshiped the worm as a god, and they theorize that the creature somehow survived its destruction, but it was trapped inside the cavern. The remainder of the movie shows Angus, James, ...