During the day, Connor, Amaya and Greg see Luna Girl's moths flying around the city, leaving notes with a crescent moon on it everywhere. Fearing that Luna Girl is up to something, they decide to confront her that night.
That night, the three kids transform into their superhero alter-ego's and meet up at HQ. Luna Girl contacts them on the PJ Picture Player, and taunts the PJ Masks how they won't be able to stop her latest plan. The PJ Masks board the Owl-Glider and leave HQ to chase Luna Girl. Luna sicks her moths onto the Owl Glider, blocking Owlette's view. Owlette tries to shake them off.
With the PJ Masks distracted, Luna Girl sends one of her moths to infiltrate HQ. In HQ, PJ Robot activates the red lights from Owlette's HQ section to lure the moths away from the Owl Glider. It works and the moths leave the Owl Glider alone. But while PJ Robot is helping his friends, he fails to notice the moth that got inside. The moth enters the vault and steals the Moon Crystal. PJ Robot fails to stop her, and the moth brings the crystal to Luna Girl. Luna Girl combines the crystal with her magnet and turns her Luna Magnet into her Luna Wand. Luna Girl and the moth who stole the crystal leave the City and head for the Lunar Fortress, while the other moths keep the PJ Masks busy.
On the moon, Luna Girl names the moth Mothzuki, gives her some powers, and makes Mothzuki her henchman. She then upgrades the Lunar Fortress with a moon beam and begins to steal various objects from the city. On Earth, the PJ Masks are about to follow Luna Girl into space when they notice the tractor beam. Catboy volunteers to stay on Earth and keep Luna Girl from stealing more stuff, while Owlette and Gekko go to the moon using the HQ's rocket function.
When Luna Girl notices the PJ's split up, she aims the moon beam at the approaching HQ instead. Gekko fires a furball at the Lunar Fortress and destroys the magnet generating the beam. He and Owlette then land the ship and infiltrate the Lunar Fortress. Unfortunately, with her new powers, Mothzuki notices the two and warns Luna Girl. She takes both PJ Masks prisoner and uses two moonballs to absorb their powers. She then contacts Catboy on Earth to inform him of his friends' capture. Luna Girl announces she will restore the magnet and continue to steal whatever she wants, with only Catboy being left to try and stop her.
Luna Girl restores the magnet on top of her fortress, and continues to pull objects from the city to the moon. She starts with a bicycle, and the museum. Thinking quickly, Catboy jumps into the moon beam, and is thus pulled towards the moon as well. Luna Girl notices him however, and shuts off the moon beam so Catboy will be stranded in space. Catboy tries his best to make it to the moon before the beam shuts down. He fails, but fortunately PJ Robot comes to his aid and brings him to the moon.
Catboy tries to get into the fortress, while PJ Robot will wait for his signal. Luna Girl sees Catboy, and is surprised he made it to the moon after all. After a brief fight, Catboy manages to sneak past Luna Girl and get into the fortress, where he finds the captured Gekko and Owlette. Luna Girl follows, and sends Mothzuki after Catboy, who chases Catboy out of the fortress again.
As Luna Girl and Mothzuki are distracted, PJ Robot enters the fortress and tries to free Gekko and Owlette. His first attempts fail, but eventually he manages to shatter the crystals holding the two heroes captive by playing opera music. He uses the same tactic to also shatter the moonballs holding Gekko and Owlette's powers, and they are thus resored to their rightful owners.
Gekko and Owlette reunite with Catboy to take on Luna Girl and Mothzuki. Owlette defeats Mothzuki. Luna Girl causes Gekko and Catboy to fall off the fortress, but PJ Robot catches them. The museum meanwhile arrives on the moon, and Luna Girl puts it next to the fortress. Gekko throws a large rock at the magnet, and Catboy uses his super cat speed to give it the extra momentum it needs. Luna Girl tries to stop them, but Owlette disarms her with her owl feathers. While the rock breaks the magnet, the Luna Wand is split up into the Luna Magnet and the moon crystal again. The remains of the mega magnet fall to the surface, and seemingly shatters the moon crystal.
Catboy saves Luna Girl before she too is crushed under the remains of the magnet. Heroes and villains both board the HQ rocketship and prepare to return to Earth, taking the museum along. Luna Girl is embittered that her plan failed, but Mothzuki cheers her up with the news that the moon crystal is still intact, and ready for her to take in the future.
Luna Girl comes up with a name for Mothzuki when they are already on the moon, so Mothzuki is most likely the only named moth at the moment.
When Luna Girl fires the moon beam from her lunar fortress to the city, the beam can be seen heading for Panama, a country in Central-America. However, this contradicts previous episodes in which the city was suggested to be located in a US or European setting.
This is the second time Owlette uses her Super Feather Shield.
This is the sixth time the PJ Masks don't transform back after chanting their victory.