Night of Death (1980)

Young Martine begins working as a nurse at Deadlock House, a secluded grande retirement home, but from the beginning not everything is as it seems, strange residents each with their own quirks and a rather macabre dietary supplement to their vegetarian diet are ruled by the strict Miss Helene, and her suspicions are soon raised when her co-worker who has taken her leave for two months leaves without her suitcase.