A rainy Gotham city night and a murder has taken place on its outskirts. At the crime scene Commissioner Gordon and the Batman find the victim, Jack Barton wearing a ghastly grin along with Jokers calling card. The Batman leaves the crime scene realizing the Joker recently escaped from the hospital for the criminally insane has it in for the former members of his gang. The Batman tries to bring former gang member Packy White (a janitor now at a boxing gym) under police protection. After a sparring match Packy is convinced to go along with the Batman's plan. He takes a drink of water to "wash the taste of Batman's knuckles away" when he suddenly falls backward with the Jokers grizzly grin upon his face. The Joker soon takes out another member of his gang with an exploding cigar filled with nitro-glycerin. The Batman tries to help another former member Bigger Melvin only to be hit from behind and falls unconscious. When the Batman comes to he finds Melvin hanging dead from the rafters and then knocked unconscious again from behind by the Joker. The Joker at first seems to want to kill the Batman but then decides against it. Regaining consciousness, the Batman heads for the last member Bins Hooley, the forger at the Home for the Aged to find he was taken out earlier that day by Mr. Genesius, realizing that this Mr. Genesius is the Joker. Rubbing his head from the Jokers attack, the Batman finds crude oil and sand and comes to the conclusion of the Jokers whereabouts, an abandoned aquarium. There he finds the Joker holding a control to lower Hooley (sitting in a wheechair) into a tank with a great white shark. They make a deal to spare Hooley and put Batman in the tank with shark instead. After the Batman is pushed in so is Hooley. The Joker laughing after breaking his promise watches. Soon the Batman frees himself from his chains and defeats the shark and then uses Hooley's wheelchair to break the glass tank. The Batman chases after the Joker who almost gets away when he slips on the oil slicked beach. The Batman overtakes the Joker and puts him out with a right cross.