Previously…

Ben and his team crash on Vilgax's home planet. Ben and Gwen meet a Vilgaxian called George who help them escape Vilgax. Vilgax knocks Kevin out. The 5 escape back to plumbers base.

Plumbers Base…

Max stood at the docking station, watching the incoming ship dock. Ben, Gwen holding Kevin, Rook and Kai emerged from the ship, a look of worry on each of their faces. "What happened?" Max asked. "Vilgax happened…" Rook sighed. Max matched their faces, then replied, "What?!" Ben shrugged, "We went to the planet of the Vilgaxians. Gwen and I met a Vilgaxian called George who told us about Vilgax." "Yeah," Gwen agreed, "Then, Vilgax came. He attacked Kevin." "I'll take him to the infirmary," Max replied, taking Kevin from Gwen, "Rook and Gwen, try and research Vilgaxians." "And me and Kai will go and find out what Vilgax meant when he said about not being the only one looking for revenge!" Ben exclaimed. Max took Kevin away, as Gwen and Rook exited the room. "So," Kai asked, "Where do we go first?" Ben gazed into her eyes, "The place where I'm hunted most… Undertown."

Undertown, 30 minutes later…

Kai and Ben strolled through the markets. "This stuff is disgusting!" Kai said in disgust. Ben laughed, "You'll get used to it." After a moment of silence, Kai asked, "Do we really get married in the future?" "Yeah," Ben replies, "I think so, anyway. I hope so…" "Really?" Kai sighs. Ben nods. Suddenly, behind them, they heard an explosion. Ben became Spidermonkey and said to Kai, "Hop on!" Kai climbed onto Spidermonkey, and they rode over to the explosion. Kai leaps off Spidermonkey and they stare at the wreckage in shock. "Khyber," Spidermonkey gasps, returning to human form. The huntsman leaps out of his wrecked ship and moves closer to Ben, a dagger in his right hand. "You teamed up with Vilgax?!" Ben screamed. "Of course, he isn't as good as me, but I'll train him," Khyber answered. Kai took a gun from her pocket and aimed it at Khyber. "Where did you get that?!" Ben exclaimed. Kai shrugged, as Khyber lunged forwards. Ben slammed down on the omnitrix, fingers-crossed for something good. "Rath?!" Ben exclaimed, covered in orange and white fur, "Of course, it had to be Rath!" Rath charged forwards as Khyber and Rath met blade to nails. Quickly, Ben changed into Eatle and whacked Khyber with his horn. Khyber threw him to the side, and sprinted towards Kai. Human Ben sat up and saw Ester throwing Khyber to the floor. With Khyber unconscious, Ester led Kai and Ben to the Krahoh base. "Khyber has been hunting you ever since you left Bellwood," Ester explained, "And now that you're back, you're in even more danger. Vilgax has an army of villains you've already faced." "That explains Vilgax's revenge theory," Ben suggested. "Ester!" a voice shouted. "Aww," Ester groaned, "I've gotta go. See ya round, Tennyson." Kai and Ben waved goodbye and walked back to Undertown. "So, who else might we be facing?" Kai asked. "I've faced a lot of villains," Ben replied, "So, I have no idea."

Meanwhile…

"There's nothing here!" Rook groaned, "I'll have to check the old documents in the Null Void Chamber, where the secret files are kept." "Okay," Gwen agreed, "And I'll check the library." "Come to me if you find anything," Rook commanded. Gwen nodded, and they separated. Gwen approached the library, but heard a voice. Her mana flared to life, and Lucky Girl took her place. Gwen burst through the door to Charmcaster. "Charmaster?!" Gwen exclaimed, "But you were trapped in the bag!" Charmcaster laughed, "Well, I know a certain squidface and… yeah." Gwen growled, "Vilgax." Gwen charged in, as Charmcaster cast her mana at Gwen. The anodite deflected Charmcaster's mana into a bookcase, which slammed onto Charmcaster. She growled and tried to get up, but Gwen, no longer in Lucky Girl form, held her in place with her foot. "I don't think so," Gwen laughed. Charmcaster growled, "Don't think for one second that I'm the only one Vilgax sent to Earth." Gwen called for Patelliday, and he came with a plasma net, trapping Charmcaster in it. Through Charmcaster's screaming, she still found the book on Vilgaxian's.

5 minutes later…

"Hello, Rook." Rook spun around, "How did you escape?" Fisttrick moved in closer, "Doesn't matter. It's why I'm here that matters," he said, a large smile crossing his face. "And why's that?" Rook replied with a stern, serious face, as usual. Fisttrick laughed, "Vilgax." Rook gasped and zapped Fisttrick with his proto tool. He fell to the floor with a grunt. "That was easy," Rook beamed.

Meanwhile…

Khyber, back in his conscious form, stood in front of Ben and Kai, blocking their way. Ben transformed into Terraspin and blew full force at Khyber. He stood there, unmoving. Ben became Humungosaur, and threw a boulder at his head. Khyber caught it. Finally, Ben changed into Blitzwolfer and used his supersonic screech at Khyber. Khyber stayed unmoving. Cautious, Blitzwolfer moved towards Khyber, and stared into his eyes. "Hello?" Blitwolfer said, confused. Deep in Khyber's eyes, he saw a familiar face that he wished he didn't see. Ben returned to human form, and stood in fear as Khyber fell to the floor. He's still unconscious, Ben realised. A grey creature floated out of Khyber's unconscious body. "Hello, Tennyson," it said, "Afraid of the dark?"