The enemies of the Kamen Riders has invaded another universe lending a hand to Sauron in order to conquer Middle Earth. In response 9 Kamen Riders followed them in order to bring them back into their own universe while changing the fate of Middle Earth.

After receiving a strange vision and message, Kamen Rider Gaim finds himself in a strange new world on a new mission. To help destroy The One Ring and put an end to the Dark Lord Sauron and his armies, before he can take rule over Middle-Earth. To do so, he will join his new friends on the quest to destroy the source of his power, and to protect the Free Peoples of Middle-Earth.