Gotham City is under siege by a series of bizarre crimes and only the world's greatest detective, Batman, can unravel the mystery! The trail leads to none other than the Penguin and his Animilitia, an animal-inspired squad of villains including Silverback, Cheetah, Killer Croc and the monstrous Man-Bat.

The Joker is aided in his Halloween quest to render modern technology useless and take over Gotham City by Solomon Grundy, Silver Banshee, Clayface and Scarecrow.

Mr. Freeze turns Killer Croc and Bane into super-sized monsters, and they bash their way through downtown Gotham until the Caped Crusader and his team of heroes join the fight in their giant robot mechs.