Legacy of Blood | 1977
When three sisters to go New York for the reading of their father's will, they learn that it has a strange stipulation. They must all spend three days with their husbands in the family mansion "in sexual harmony" or they cannot divide the family fortune. When they arrive at their old home on an isolated island, they find that the same caretakers that were there when they were children: Two unmarried sisters and their brain-damaged brother. That night there are some bloody warnings found around the house, and the following morning one husband is found hanged. With no phone, the rest of the group feel they must stay for the rest of the weekend, and the mysterious killer continues to murder them. Eventually a terrible family secret is revealed.