While working underground to fix a water main, Brooklyn plumbers—and brothers—Mario and Luigi are transported down a mysterious pipe and wander into a magical new world. But when the brothers are separated, Mario embarks on an epic quest to find Luigi.

All the major DC superheroes are starring in their own films, all but the Teen Titans, so Robin is determined to remedy this situation by getting over his role as a sidekick and becoming a movie star. Thus, with a few madcap ideas and an inspirational song in their hearts, the Teen Titans head to Hollywood to fulfill their dreams.