Penn and his team are zapped into a world where they are enormous yet misunderstood monsters. They must convince the human President of a nearby island city that the monsters mean them no harm.

Boone gets a bad report card from Phyllis, making his parents mad. He tries to fix this while on a mission in the Giant Monster World.

Penn, Sashi, and Boone must travel to the three most dangerous places in the multiverse in order to free Penn's parents as Rippen plans to conquer the Most Dangerous World Imaginable with Larry and those with him after having to close its portal from the other side.