Crazy desires of a murderer (1977)

A group of hip friends gather at a Gothic castle owned by a wheelchair- bound older relative of one of the girls. One couple in the group, unbeknownst to the others, is smuggling heroin in some Chinese artifacts the protagonist has brought back from the Orient to give to her elderly relative. Meanwhile the deranged uncle of the protagonist, who supposedly killed the protagonist's mother (his own sister) and cut out her eyes, is wandering the catacombs spying on everyone. When one of the guests is murdered and her eyes subsequently disappear, suspicion naturally falls on the mad uncle. But is he being set up?