In the summer of 1890, a reporter for the London Daily Bulletin receives an anonymous note about the dismissal of Edward Utterson, adopted son of eminent attorney John Utterson, from the Royal Academy of Sciences for persisting in experiments bordering on witchcraft. At the Science Exposition, Edward, undaunted by his expulsion, enthusiastically plans to continue his studies abroad and proposes to his sweetheart Lynn, who happily accepts. Edward's mentor, well-known psychologist Curtis Lanyon, is concerned about Edward's situation, and takes him to a local club, where he divulges Edward's true parentage: his mother was an actress and his father a distinguished scientist whose failed research brought about depression and madness that led to the murder of his wife and his own death. Realizing that Lanyon is relating the infamous story of Dr. Henry Jekyll, a stunned Edward hastens to tell Lynn. Edward resolves to take up his true identity, and asks Lynn to postpone their marriage until he can clear the mystery and suspicion that surrounds the Jekyll name. That evening, Edward visits the abandoned Jekyll residence and is discovered by the local constable. The newspapers report the story, and Edward's claims to be Jekyll's son, and imply that the residence is haunted. Edward restores the Jekyll home and moves in, setting up a laboratory. Lanyon then provides Edward with his father's handwritten notes on experiments in changing human personality, and Edward concludes that if he can recreate his father's experiment successfully, he can clear his name. A few days later, Edward receives a letter from former vaudevillian Lottie Sarelle, who claims to have been a friend of his mother. When Edward visits Lottie, she divulges that she witnessed Edward's father murder his mother in a fury, but Edward refuses to believe her. The press continues to hound Edward and publicize fantastic rumors about the Jekylls, while Edward proceeds daily with unsuccessful trials of his father's experiment. Lynn grows concerned about Edward's obsession, although she is relieved to discover that he has hired his father's stoic old assistant, Michaels. One night, Michaels is awakened by sounds in the laboratory. Down in the lab, Lanyon secretly adds an ingredient to Edward's partially completed formula and slips out before Michaels investigates. The next day Edward's experiment is successful for the first time, and he summons the press, Lynn and Lanyon for a demonstration, which is a failure. Depressed, Edward accepts an invitation from Lottie's son Joe to meet for a few drinks. Later that evening when a young boy, one of the constant crowd of hecklers outside Edward's house, is assaulted, Edward is arrested as a suspect. At the subsequent hearing, the Sarelles testify against Edward, who is released into Lanyon's custody. Edward sneaks away to question the Sarelles only to discover they have fled. An empty box leads Edward to a music store, where he finds Joe's pawned accordion and the family's address. At the Sarelles', Edward encounters Joe's wife Hazel, but before they can talk, Joe appears and the men fight. As a constable breaks up their row, Hazel leaves a note for Edward in the accordion, asking him to meet her at Lottie's old flat that night. When Edward arrives that evening, he finds Hazel murdered and sees a man fleeing. The police search for Edward, who hides at Lynn's. She summons John, but he disbelieves Edward's story and suggests he killed Hazel in a fit of madness. Meanwhile, Lanyon meets with Joe, who demands more money for the part he and his the family have played in deceiving Edward. Later, Edward voices his mounting suspicion to John and Lynn about Lanyon and goes to visit Michaels, who startles Edward by mentioning a particular drug in his father's experiments. Aware that that information is not in the notes, Edward realizes Lanyon has set him up and asks Lynn to retrieve the notes from Lanyon. Though doubtful, she agrees, but tells Lanyon about Edward's suspicions. When she brings Edward the notes, he notices that they are faked and risks going to his laboratory to get the originals. Lanyon arrives before him and attempts to burn the notes but Edward's arrival interferes. Lanyon explains that Jekyll's experiments ruined him and he wanted the Jekyll estate to recoup his losses. Lanyon then knocks Edward out and leaves him in the burning laboratory, where he is rescued by Michaels. The crowd that has gathered outside believe Lanyon to be Edward and force him back into the house. While trying to escape across the roof, Lanyon falls to his death in the flames.