General Pherides (Boris Karloff) and reporter Oliver Davis (Marc Cramer) visit the Isle of the Dead to pay their respects to the General’s long-dead wife. The island is supposed to be deserted but the general and Davis find people there after following the voice of a singung woman.
Swiss archeologist Dr. Aubrecht (Jason Robards, Sr.), his housekeeper Madame Kyra (Helen Thimig), British diplomat Mr. St. Aubyn (Alan Napier) and his pale and sickly wife (Katherine Emery), her youthful Greek companion Thea (Ellen Drew), and English tinsmith Andrew Robbins (Skelton Knaggs) are all on the island.
The houskeeper Krya believes that Thea is a vorvolaka, a kind of vampire creature that brings plagues and tells the general who laughs it off as superstition. Davis starts to fall for Thea.
The next morning Robbins is found dead and Dr. Drossos (Ernst Deutsch) diagnosis the cause of death as septicemic plague and quarantines the island until a hot dry wind comes to the island.
Mr. St. Aubyn dies and they bury him quickly much to his wife’s chagrin who fears premature burial. Soon the general starts to believe that Thea is a vorvolaka.
Producer Val Lewton made several low budget horror movies for RKO Studios and all of them were excellent thrillers that dealt with more psychological horrors rather than actual monsters. Isle of the Dead works as paranoia and superstition grab hold of the quarantined people. Karloff’s performance is fantastic.