Rosemary and Floretta Turnbull have deeded their family estate to charity. However, the property, which was willed to them by their father, is not quite yet theirs as the will stipulated that they needed to live in the house everyday for twenty consecutive years, their time period with two weeks to go. However they may not make it to the twenty year mark as things seem to be happening around the house that are scaring them into moving out. Their chauffeur is killed in the house (they're not sure if it was suicide or murder), they hear strange noises and there are minor thefts without any sign of break-ins. Nancy Drew does whatever she can to keep the Turnbull sisters in the house, even faking evidence to the police. But she and her next door neighbor, Ted Nickerson, investigate to find plausible explanations for these happenings and if indeed someone is trying to drive the sisters out of the house.
—Huggo