By day, Greg wants to build a very awesome model rocket ship, but all the supplies to build one is gone. Connor cheers Greg up about the trip to the science museum, but the teacher said that the trip was cancelled because there's no electricity. By night, it is revealed that Romeo wants to take over the town with his latest invention: The Big Box of Bad! Robot says that Romeo is going to rename the town "Romeoville" or "Romeopolis". Once Romeo said everything about Big Box of Bad, Gekko gets mad, but then he finds out that Romeo booby-trapped the entire museum. Gekko accidentally steps on a Spring Trap, then Catboy catches Gekko before he fell into the water at the fountain. Then Owlette catches Gekko and Catboy before they fell. Then Romeo went back inside. Romeo is inside, until he heard the ice cream truck sound (which is a trick made by the PJ Masks). Gekko suddenly pops up, then Romeo become so disappointed. Gekko steps into the same booby trap, but this time he attached to it because of hiss "Super Lizard Grip". Gekko stepped on another booby trap made by Romeo, but he fell for it. Then a massive ball fell, and Gekko run until it hits his Gecko-mobile. Gekko gets steamed when the boulder crashes into his vehicle, but then Catboy thinks of something: stinky cheese. When Romeo finds out about the stinky cheese, he stinks up the PJ Masks with "super super stink". After a while, Romeo's Big Box of Bad is finally complete, and "Romeopolis" is born! Gekko figured out that there were more ways to solve a problem. Gekko said "It's time to be a hero!" and had a plan to distract Romeo from taking over the world. When Romeo went inside the museum, Robot comes to Romeo and told him that is lab was moving. Romeo was surprised because the lab battery is not charged, then he saw inside Catboy pretending to drive Romeo's Lab. Then, Gekko revealed that he was moving the Lab. Romeo came to the lab and once more he saw Owlette with the Big Box of Bad, she knocked it over to the booby-trap. The Big Box of Bad was destroyed, and the city was restored to its original state. Romeo figured out that his lab was charged as this happened. Romeo stepped on a booby-trap, then he had his time hanging out. Robot catches Romeo and mentions that they stepped on a booby-trap. The PJ Masks said their motto, and the day was saved in the night.
There is usually more than one way to solve a problem.
In this episode, Romeo introduces his Big Box of Bad.
Romeo later reveals that he likes ice cream, especially double tofu pistachio ice cream. This was during an attempt by the PJ Masks to lure him towards a fake "ice cream truck".