Legend says that swamp giant Solomon Grundy will return to Gotham City on a Halloween with a lunar eclipse. Supposedly, Grundy will return to get revenge on the descendants of Gotham's founding fathers. On Halloween night, the eclipse begins, and Batman receives word that Grundy is wreaking havoc in Gotham. The caped crusader is skeptical about the legend. Still, he must battle this dangerous villain who is bent on terrorizing certain residents of the city.