Ruth Bennett Bennett has inherited an old house in Gettysburg, Pennsylvania, tucked away in the Amish countryside, and she leaves behind her career as a secretary at the U.S. Department of Agriculture. She moves in with her niece, Sara Dunning (Kitty Winn). The house, built during the Revolutionary era, carries a heavy sense of history and is said to be haunted by the original inhabitants, among them General Campbell, a war figure with rumored ties to British enemies, and his daughter Ammie, who vanished after eloping with her lover, Anthony.
Ruth and Sara host a small gathering that includes their neighbor and professor Pat McDougal (Richard Egan) and his student Stan Whitman (Michael Anderson Jr.). On a guest’s suggestion, they decide to hold a séance inside the house. That night, Ruth experiences a bizarre nightmare in which Sara approaches in the garden, only to grow inexplicably terrified and flee. When Ruth awakens, she finds Sara downstairs, visibly frightened, having discovered an historic portrait of General Campbell impaled on a fireplace poker.
Pat, Sara, Stan, and Sylvia Wall (Doreen Lang), a medium, arrive for the séance. In the kitchen, Pat’s behavior toward Ruth turns aggressive, adding a tense undercurrent to the evening. During the séance, Sara begins to scream, and the portrait of General Campbell cascades from the mantel. That night, Ruth is awakened by a hysterical Sara, who attacks Ruth. Pat suggests that Sara may be suffering from schizophrenia, but Stan counters with a troubling observation: during the previous séance, he witnessed the face of another woman on Sara’s body.
Outside, Ruth, Pat, and Stan hear a voice calling, “Ammie! Come home!” They find Sara again in distress. Stan starts digging into diaries and artifacts in the house’s attic and experiences a string of unsettling supernatural events himself. By researching historical records, the group concludes that General Campbell murdered Ammie and Anthony the night they tried to elope, and that their spirits have begun to possess Pat’s and Sara’s bodies.
They seek Sylvia for another séance to exorcise the spirits from Sara and Pat, which triggers violent poltergeist activity and sends Sylvia fleeing in terror. While exploring the house further, Stan discovers a boarded passageway in the basement. Soon after, Pat becomes momentarily possessed by Anthony, and Sara by Ammie. Determined to end the haunting, Ruth, Pat, Sara, and Stan convene again at the house and break through the basement wall. They uncover a dirt-walled room containing human bones and an old firepoker—the murder weapon the General used to kill Ammie and Anthony before burying them in the basement. Moments later, Pat becomes possessed by the General and attempts to attack the possessed Sara, but Ammie—speaking through Sara’s body—tells him that his crime has been uncovered. With the truth revealed, the spirits depart from Pat and Sara, leaving the house quiet but forever marked by the memories of its past.
