Red Rings of Fear (1978)

Commissioner Di Salvo investigates the death of Angela Russo, a young woman who has also been brutally raped. His investigation focuses on Santa Teresa, the exclusive women's school she attended. The members of the group “Las Inseparables”, to which Angela belonged, begin to suffer strange incidents and receive threatening messages. Through various clues, Di Salvo will have to find the murderer before another tragedy occurs.