Boom! - Joseph Losey

Film version of playwright Tennessee Williams' "The Milk Train Doesn't Stop Here Anymore" involves very wealthy Flora 'Sissy' Goforth, supposedly dying, and living in a large mansion on a secluded island with her servants and nurses; into her life comes a mysterious man, Angelo Del Morte and "the Witch of Capri." The mysterious man may or may not be "The Angel of Death".