The episode opens in HQ, where PJ Robot is cleaning up Catboy's room. Then the PJ Picture Player alerts him to a comet approaching the earth. At the same time, HQ begins to glow with a green aura.
PJ Robot alerts Connor, Amaya and Greg about his discovery. So that night they go to HQ, where PJ Robot persuades the three heroes to visit the comet. He believes it could power-up HQ, and thus the PJ Masks themselves. Owlette insists they first check for any villains, but they can only find Romeo, and he’s busy maintaining Robot. Assured that the city is safe, the heroes depart with the HQ rocketship.
Along the way they pick up a signal from the Lunar Fortress and make a detour to the moon to investigate. They find nothing except tire tracks from Romeo's Lab, but Owlette deduces they must be from the last time Romeo was here, since they saw him in the city. As they leave the moon again, none of the heroes notices a small device has been attached to the rocketship.
PJ Robot requests to fly the rocket, and Owlette lets him. They reach the comet, but when they try to land, the rocketship is sucked into the comet instead. Once the rocketship is trapped in the comet, Romeo contacts the PJ Masks. The whole thing was a trap set up by him and Luna Girl; the Romeo they saw in the city was just a hologram, the device attached to HQ is what made it glow the night before, and the comet is actually a forcefield. Now that the PJ Masks and their HQ are trapped inside, the villains plan to build a new HQ for themselves.
The PJ Masks unleash HQ’s weapons onto the forcefield in an attempt to escape, but none are effective. They leave the rocektship and try their own powers on the forcefield, but this too has no effect. Worse, due to the zero gravity the PJ Masks drift away from the rocket. PJ Robot rescues them. He then detaches Romeo’s device and attaches it to the rocketship’s energy blast generator, and instructs the PJ Masks to channel their powers into it. This supercharges the energy blast, and finally allows the PJ Masks to destroy the force field.
Back on Earth, Luna Girl and Romeo are arguing about the new HQ they plan to build. Then HQ returns to Earth and blasts them both away. Seeing the angry PJ Masks about to attack them, the villains flee.
Think before you act.
This is the second time Luna Girl and Romeo work together, even though they did argue in the end.