Dr. Henry Jekyll dedicates his life to the curing of all known illnesses, however his lecherous friend, Professor Robertson, remarks that Jekyll's experiments take so long to actually be discovered, he will no doubt be dead by the time he is able to achieve anything. Haunted by this remark, Jekyll abandons his studies and obsessively begins searching for an elixir of life, using female hormones taken from fresh cadavers supplied by murderers Burke and Hare murders, reasoning that these hormones will help him to extend his life since women traditionally live longer than men and have stronger systems. In the apartment above Jekyll's lives a family: an elderly mother, her daughter Susan Spencer, and Susan's brother Howard. Susan is attracted to Jekyll, and he too returns her affections, but is too obsessed with his work to make advances. Once mixing the female hormones into a serum and drinking it, it not only has the effect of changing Jekyll's character (for the worse) but also of changing his sex, transforming him into femme fatale. Susan becomes jealous when she discovers this mysterious woman, but when she confronts Jekyll, to explain the sudden appearance of his female alter ego, he calls her Mrs. Edwina Hyde, saying she is his widowed sister who has come to live with him. Howard, on the other hand, develops a lust for Mrs. Hyde.