Nancy (Loretta Young) and Jeff Troy (Brian Aherne) move into a somber-looking basement apartment building on 13 Gay Street, Greenwich Village, where the residents all act very strangely. Nancy recognizes one of the residents, Anne Carstairs (Jeff Donnell), who acts very oddly and not at all the way Nancy remembers her. At dinner, Nancy overhears a man, later identified as Louis Kaufman, talking on the telephone telling someone to meet him in the basement apartment. Louis goes to the basement apartment and is later found dead in the backyard, after having been drowned in the apartment's bathtub.