SpongeBob and Patrick are the biggest fans of Mermaid Man and Barnacle Boy in all of Bikini Bottom. They have every episode on VHS, every action figure, and even a signed poster of the dynamic duo hanging on their bedroom wall.
One day, while watching their favorite show, SpongeBob and Patrick stumble upon a mysterious signal being broadcast from the old Mermaid Man and Barnacle Boy TV studio. Without hesitation, they set out to investigate and find themselves in the middle of a real-life adventure.
As they explore the abandoned studio, SpongeBob and Patrick discover a hidden room filled with Mermaid Man and Barnacle Boy costumes and gadgets. They can't resist the urge to dress up and become their heroes, ready to take on whatever villainous challenge comes their way.