Mr. Hyde is the criminal alter-ego of London physician Dr. Jackal. When his philandering wife neglects him, Dr. Jackal of St. Cohen’s Hospital tries to make several attempts to eat at work but gets constantly interrupted and distracted by nurses and patients. Finally, to got something to eat, he mixed up the chemicals and pills in his office and transformed into the ruthless but simple-minded Mister Hyde. As Hyde, he launched a crime spree of picking pockets and public scams to steal all he could. The police finally caught him peeping on a young lady changing her clothes, but when they took him to a restaurant on the way to the jail, he reverted back to Dr. Jackal. The police didn't notice this and let Dr. Jackal wander off while they looked for Mr. Hyde.
By the next day, Dr. Jackal was still starving and drank from his earlier potion again. He reverted to Mr. Hyde again and rounded up a gang to help him start robbing banks. The police chief called in Wonder-Gran from the Sunny Days Nudist Camp for help. Posing as a teller, Wonder-Gran blasted Mister Hyde and his gang with a cannon when they came to rob the bank where she was working. She pursued them to St. Eamon's Golf club where Hyde and his gang harassed and robbed the members. The police soon arrived to stop the fracas, and Wonder-Gran took Mr. Hyde home to reform him, but he was a bull in a china shop as he distractingly wrecked and smashed up her modest home. Once he got food into his stomach to counteract the potion, he reverted back to kindly and misunderstood Dr. Jackal. The presence of the normal looking doctor frightened Wonder Gran so badly she rode away on her jet-powered bicycle.
- Dr. Jackal and Mr. Hyde were both played by Benny Hill.
- This character is a spoof of the titular character from the book, "The Strange Case of Dr. Jekyll and Mister Hyde" by Robert Louis Stevenson.