The heroic G.I. Joe action force must oppose the ruthless Cobra organization that has secretly allied with a subterranean reptilian people who were their founders.

A poor boy and a prince exchange identities and lives while the villainous Captain of the Guard plots to take advantage of this.

The Autobots must stop a colossal planet consuming robot who goes after the Autobot Matrix of Leadership. At the same time, they must defend themselves against an all-out attack from the Decepticons.