Condemned to Live (1935) on Netflix

Plot summary

A small village is shaken by a string of murders. Three victims lie in the caves with their throats torn open and their blood drained, and the villagers blame a giant vampire bat that kills only in the dark. Professor Paul Kristan, respected for his goodness, urges his neighbors to keep their lights burning once darkness falls. He is engaged to Marguerite Mane, and her childhood friend David, who loves her, argues that she mistakes admiration for love. Paul keeps house with his servant Zan, a hunchback, and his housekeeper, Mother Molly. His foster father, Dr. Anders Bizet, arrives for a visit, and Paul tells him about headaches that leave him vague and exhausted.