Gorilla Grodd is one of a number of intelligent, talking gorillas native to Gorilla City, a once-secret settlement in Africa. Grodd possesses an enhanced intellect and psionic force-of-mind abilities, resulting from exposure to extraterrestrial rock that was found on the continent. He seeks to gain control of both Gorilla City, as well as the rest on the world, and utilizes mind control and devolution technologies in his bids for conquest. Gorilla Grodd is a member of the Secret Society of Super-Villains, and a frequent opponent of the Flash.
Gorilla Grodd has launched an invasion of the Little Bohemia district of the city of Metropolis. He has sent his gorilla army out to devolve Metropolis' citizens, while he coordinates efforts from his hidden lab. The Flash located this base, but contact with the speedster was lost after he entered to bring an end to Grodd's plans. The lab must be infiltrated, and the Flash freed, if Grodd is to be stopped.
Lex Luthor asks that you assist Grodd and his minions against the S.T.A.R. Labs forces that are picking up exobyte canisters that have fallen around Centennial Park in Metropolis. Once you have battled through the S.T.A.R. Labs forces, you will assist Grodd in a fight against Flash (Barry Allen) and Flash (Jay Garrick).