Boom! is a 1968 film starring Elizabeth Taylor, Richard Burton and Noel Coward. It was directed by Joseph Losey and adapted from Tennessee Williams' play The Milk Train Doesn't Stop Here Anymore.
In the film, Flora 'Sissy' Goforth (Taylor, in a part written for an older woman) is supposedly dying, and living in a large mansion on a secluded island; into her life comes a mysterious man, Angelo Del Morte (then-husband Burton, in a part intended for a very young man) and "the Witch of Capri" (Coward). The mysterious man may or may not be "The Angel of Death".