12 year-old Christina (Tissy) Matthews spends four weeks of her summer vacation with her mother's relatives at their newly purchased house in the country. When she arrives she meets Norma, the young girl who lives across the road. Norma tells Tissy about the ghost of Mary O'Hanlan that haunts her cousin's house. As the ghost becomes more and more apparent to Tissy, she and Norma decide to investigate why the ghost is not at rest and to help her. They hold a séance and discover that the ghost of Mary O'Hanlan wants to know the truth about what happened to her father who disappeared without a trace 95 years earlier. The townspeople had started a rumour that Mary's mother murdered her father and buried him on the property and Mary and her mother became life-long outcasts in the community. Tissy and Norma enlist the aid of local reporter, Wade Hemming, and together they discover the truth behind the mystery.