Classic horror set in London during the early 1900s. The film follows a young woman, Phyllis (June Lockhart), who unwittingly transforms into a werewolf when night falls. Suspected of committing a series of gruesome murders, she breaks off her relationship with her partner Barry (Don Porter). However, Barry is devoted to Phyllis and decides to investigate the case on his own. He soon discovers the identity of the real murderer and is reunited with Phyllis.