Abbott and Costello Meet Dr. Jekyll and Mr. Hyde is a 1953 comedy horror film directed by Charles Lamont and starring the comedy team of Abbott and Costello, and co-starring Boris Karloff. Loosely based on the novel The Strange Case of Dr. Jekyll and Mr. Hyde by Robert Louis Stevenson, the film follows the story of two American detectives visiting Edwardian London who become involved with the hunt for Dr. Jekyll, who is responsible for a series of murders.
Slim (Bud Abbott) and Tubby (Lou Costello) are American cops in London studying police tactics. A newspaper reporter, Bruce Adams (Craig Stevens), gets into an altercation at Hyde Park that was instigated by Vicky Edwards (Helen Westcott), a suffragette. Bruce and Vicky wind up in jail, while Slim and Tubby are kicked off the police force. Dr. Henry Jekyll, Vicky's guardian, bails them out. Jekyll has been conducting home experiments in which he injects a potion and transforms into Mr. Hyde, a monster who murders a fellow doctor when he scoffed at Jekyll's experiments. Jekyll has more thoughts of murder when he notices that Vicky and Bruce are mutually attracted. Tubby and Slim witness the doctor's shenanigans at a music hall, where they begin to chase him with Bruce at their side. Tubby traps Hyde in a wax museum, but by the time he brings the Inspector (Reginald Denny) and Slim to the scene, the monster has already reverted back to Dr. Jekyll. The "good" doctor then asks Slim and Tubby to escort him to his home, where Tubby drinks a potion that transforms him into a large mouse. Slim and Tubby bring news of Jekyll's activities to the Inspector, who refuses to believe them. Vicky announces her engagement to Bruce and Mr. Hyde reemerges, this time with intent to murder Vicky. Bruce saves her, but Hyde escapes. Tubby accidentally falls onto a serum-filled syringe, transforming Tubby into a Hyde-like monster as well. Bruce chases after Hyde, while Slim pursues Tubby, each believing still that there is only a single monster. Bruce ends up back at Jekyll's home, where Hyde falls from an upstairs window to his death, revealing to everyone his true identity when he reverts to normal form. Slim then brings Tubby (still in monster form) to the Inspector. Before reverting to human form, Tubby bites the Inspector and four officers, transforming them into monsters who begin to chase Slim and Tubby.