Eager to help their heroes Mermaidman and Barnacleboy, SpongeBob and Patrick become superheroes Man Sponge and Boy Patrick, and free the villain Man Ray from prison after he promises to turn from his evil ways.
When Barnacleboy tires of being Mermaidman's sidekick and joins the other side, Man Sponge, Boy Patrick, Sandy, and Squidward join Mermaidman, who restarts his old group of superheroes to defeat their rivals and try to win Barnacleboy back.