Lorna Webster is returning to her hometown of Eben Rock, Massachusetts when a mysterious old woman with a dog stops the bus and tries to board using colonial-era currency. The woman introduces herself to Lorna as Jezebel Trister and says she knew Lorna's great-great-great-grandfather, Judge Elijiah Webster, three hundred years before. Immediately afterward, the bus plummets off a cliff into the river. At Ruth Gibson's Pilgrim's Tavern a few hours later, Lorna falls into the arms of her ex-fiancé and Ruth's brother, Dr. Matt Adams, mumbling incoherently about the woman and the accident. The men drag all the bodies in the river but cannot find the old woman. When Reverend Jim Stevens and Matt find a growling dog, Jim recalls that the bus driver's throat had been torn by an animal. The next day in the Webster home, Matt proclaims his love for Lorna again and gives her the black veil she was carrying after the accident, which Lorna recognizes as Jezebel's. Bessie, the Websters' servant, tells Matt how the Judge burned many women at the stake as witches. Lorna begins to believe she is possessed by Jezebel after she puts on the veil and sees the face of the old woman in the mirror, and receives flowers from Matt, which immediately die. He urges her to speak to Jim about the research he conducts in the church crypt on the town's witchcraft history. That night, Jezebel's dog howls in the cemetery and wakes Lorna, who goes to the crypt and finds a 1644 confession from Jezebel stating that the Devil has agreed to transplant her soul into the bodies of young women for the next three hundred years, at the end of which she will go to hell. Lorna, now convinced that she houses Jezebel's soul, commits a series of minor crimes, including accidentally killing the goldfish of Ruth's daughter Peggy. During a violent storm, Peggy wanders into the Webster house to see Lorna fighting off Jezebel's dog, which has been following her. Peggy is frightened and rushes out into the storm. When a townsman finds the young girl collapsed from pneumonia, he spreads rumors that Lorna is a witch. Peggy sinks into a prolonged, cryptic illness, and all the townspeople, including a bereaved Ruth and Lorna herself, believe that Lorna is the culprit. Matt and Jim discover an entry in Elijiah's diary explaining how he forced Jezebel to write a false confession. As they rush to Lorna with this proof that the witchcraft is all in her head, Jim realizes that the day is exactly three hundred years from the girl's death. Before they reach Lorna, townsmen throw stones into her window, driving her out into the countryside. Plagued by accusatory voices, she falls off a cliff into the river. Matt drags her to the shore as Jim finds the body of Jezebel nearby. Days later, he reveals to Matt and a recovered Lorna and Peggy that the old woman was an escaped mental hospital patient who knew all the old legends of Eben Rock, and believed she was Jezebel.