A starship docks with an Incursean cruiser, dropping an Incursean named Frolic off. He stops to talk to Commander Raff, one of the commanders. He explains that when they were exploring an enemy star system, they were ambushed by the bounty hunter Sevenseven and Princess Attea went missing. They report to Emperor Milleous, and he kills Frolic, sending Raff to the nearest inhabited planet: Earth.
Ben, Gwen and Kevin are arguing in Kevin's Car for where to go. Incurseans then appear and point their guns at the three, but Raff appears and stops them, as Kevin reveals he used to do business with Raff back when Kevin was a villain. Raff explains the situation to Kevin and Ben's Team. Ben's team agrees to help after Milleous threatens to blow Earth to pieces with the Conquest Ray. Gwen uses the clothing to track Attea to a dam.
Sevenseven destroys the dam while trying to shoot Attea and it crushes Kevin's Car, traps Gwen in a bubble and nearly drowns Sevenseven, Attea, and Kevin in stone form. Ben decides to use the untested Celestialsapien transformation Alien X to stop the water and fix the dam. However, Sevenseven snatches Attea and Alien X is frozen in place. Ben soon realizes that in order for Alien X to do anything, he must convince one of the two personalities, Bellicus, the voice of rage and aggression and Serena, the voice of love and compassion, to agree with him.
Raff teleports Gwen and Kevin, along with the Incurseans and Kevin's car to Milleous. Milleous destroys Pluto to demonstrate the Conquest Ray's power. Even worse, Ben finds out that Bellicus and Serena do not want him to change back. Kevin absorbs his car's tires and takes the Royal Detonator, and flees from battle. Ben makes Bellicus and Serena agree on saving the Earth, but is unable to convince them on what to do. Gwen and Kevin get away from the Incurseans chasing them and run into Attea and Sevenseven. Sevenseven releases Attea, but it's revealed Attea paid Sevenseven twice as much to overthrow Milleous.
Attea takes the Conquest Ray and imprisons Milleous, Gwen, Kevin and Alien X. When Ben sees this, he forces Bellicus and Serena to release him from Alien X's body. Before Attea can fire the Conquest Ray, Ben turns into Swampfire and defeats Sevenseven and the Incurseans, before Milleous arrives and forces Attea to surrender.
Attea is thrown in stasis jail with her mother and Milleous lets Ben's team return to Earth without destroying the planet. Ben makes a vow never to turn into Alien X again, despite all the power a Celestialsapien possesses.