5. Escape from Aggregor

Complete story — includes the ending

Ben, Gwen, and Kevin defeat an alien rampaging through the streets of Bellwood. Through a universal translator, they learn that the alien, Galapagus, was only trying to get Ben's attention in order to seek his help. Galapagus explains that he was one of the five aliens from the Andromeda Galaxy captured by Aggregor, who brought him into a cell on his spaceship along with the other prisoners: Bivalvan, Ra'ad, P'andor, and Andreas. The aliens manage to escape, but are divided on what action to take: Bivalvan, Ra'ad, and Galapagus send a distress signal out to nearby Plumbers, while P'andor and Andreas confront Aggregor. Aggregor defeats and recaptures them, subsequently killing Magister Prior Gilhil, the Plumber responding to their distress call. Galapagus seemingly betrays the other aliens to Aggregor, but instead turns on Aggregor and helps them flee to a nearby spaceship, which they take to Earth and then go their separate ways. Ben sends Galapagus home via a Plumber ship, but the pilot is revealed to be Aggregor in disguise, who recaptures Galapagus. Ultimatrix alien debuts: Brainstorm