The aliens traveled billions of light years to study humans because they're fascinated with them. When the Mask was adrift in space after being ejected out of the space shuttle by the alien-paronoid astronaut, Gil Headstrong, the aliens abducted him and put him on a lab table to study him. But, the Mask annoys the aliens with his usually obnoxious antics when studying his body. The Mask was free from the lab table after a tug-of-war with his nose being pulled by the alien leader and Gil Headstrong's space shuttle was abducted by the aliens, hoping he's a better test subject. But, Headstrong fainted at the sight of the aliens and the Mask battles with the aliens. Irritated enough, the alien leader unleashes a slime power from his mouth to capture the Mask, trapping him in a cocoon.
The aliens place the Mask and Headstrong in the space shuttle to get rid of them. Thanks to the Mask, the aliens believe humans are annoying like him and want to get rid of them for good. They placed a doomsday device on the space shuttle that will vaporize all moisture on Earth, making the planet uninhabitable. The Mask frees himself from his coccoon and defeats PAL, the space shuttle motherboard, to regain control of the shuttle. He (dressed as a handyman) unscrews the doomsday device from the shuttle and sends it back into space with a baseball bat before the shuttle lands on Earth.
Back in the aliens' spaceship, the alien leader insults humans and is in relief, believing they successfully killed them all off with the doomsday device. But, the device returns to the aliens' spaceship and destroys it, injuring (and possibly slowly killing) the aliens. The alien leader, groaningly in pain, says, "Stupid humans!"
- The aliens' appearance is recycled from Nimrel, the evil Mask version of Merlin the wizard, from the Halloween episode, All Hallow's Eve.
- One of the aliens made a cameo in the episode, The Green Marine, while the Mask was watching a movie called, Hula Creatures From Demented Z, on the X-AW battleship's sonar.