John Russell (George C. Scott), a composer living in New York, New York, moves cross-country to Washington state following the deaths of his wife and daughter in a traffic accident while on a winter vacation in upstate New York. In suburban Seattle, John rents a large, old and eerieVictorian-era mansion and begins piecing his life back together.
However, John soon discovers that he has unexpected and unwelcome company in his new home: the unhappy ghost of a murdered young boy. The ghost makes its presence felt by various phenomena such as shattering windows, abruptly opening and shutting doors, and manifesting itself dramatically during a seance. John investigates the identity of the dead child and finds that the mystery is linked to a powerful local family, the heir of which is a wealthy United States senator, Joseph Carmichael.
John subsequently discovers that the real Joseph Carmichael was murdered by his father, Richard. Joseph was a crippled, sickly child, and in the event of his death before his 21st birthday, the family fortune (which he inherited from his late maternal grandfather) would pass to charity. Desperate to keep control of the fortune, Joseph's father drowned young Joseph in the bathtub, secretly replaced him with a healthy orphan, and took him to Europe in the guise of seeking a treatment or cure. He returned several years later with the impostor, now grown and "cured" of his illness, and continued as if nothing had happened.