Ben, Gwen, Kevin and Magister are on the run from the giant dragon creature, but they soon run into the Forever Knights. Kevin confronts them first by absorbing some of the rock from the walls and lifting up part of the floor and slamming it back down, sending a shockwave towards the Forever Knights and making them fall. The Forever Knights get back up again and firing their Laser Lances at them, so Gwen puts up a magic shield to protect herself, Ben, Magister and Kevin. Ben sees the dragon creature from before trying to attack them again, so he uses the Omnitrix to transform into another new alien hero, Echo Echo, who has the ability to duplicate himself and produce sonic blasts. Echo Echo duplicates himself several times so he and his clones can knock down the dragon.
Meanwhile, as Kevin finishes getting rid of some of the Forever Knights, one of them is about to shoot him from behind, but Magister sees him and shoots his laser gun at him first. As a result, the Forever Knight's Laser Lance got damaged, and Magister warns him not to use it, but the Forever Knight ignores him and tries to use it anyway, but it explodes due to the damage and it ends up killing him. Magister is able to push Kevin away from the explosion in order to save him. Kevin then says he owes him one for saving his life.Kevin, Gwen and Magister manage to defeat the remaining Forever Knights, but Echo Echo is unable to defeat the dragon creature, so he and his clones use their Sonic Blast attack to defeat it. Magister gathers up all Laser Lances in one huge pile so that Echo Echo can destroy them using his Sonic Blast.
In addition to destroying the alien weapons, the Sonic Blast also damages Magister's suit, causing a blue liquid to start leaking from it. Magister falls to the floor in pain, and Ben, Gwen and Kevin want to help him, but he says there's no time. Magister wants them to finish the mission and figure out where the level five technology is coming from. Before he dies, Magister tells them that if they solve the case, they may find out where Max is, as well as the alien conspiracy he was investigating. However, Ben says he doesn't know how to do it without Max, but Magister tells him he is Ben Tennyson, so he can do anything. Magister then dies, leaving just his empty suit. Motivated by Magister's last words, Ben is determined to finish the mission and asks Kevin for his help.
The three of them go outside, where Gwen is using her magic to levitate and trace the vibrations from the Laser Lance that Kevin kept as a souvenir back to the people who used to own it, while Ben and Kevin wait in the car. Soon, the Laser Lance starts moving forward, so Gwen tells Kevin and Ben to follow her. They arrive at a mine shaft and hide from the security guard that's watching the entrance. Before Ben and Gwen can even come up with a plan to get past the guard, Kevin has already punched him out so they can get in. Gwen thinks Kevin hit him too hard, but takes off the guard's mask, revealing its true identity as a DNAlien, and gives the mask to Ben. As they ride the elevator down to the mine below, they see several DNAliens working there and a large spaceship.
Ben is positive that Max is in that ship, so he decides to use the DNAlien's mask they stole earlier to disguise himself as a DNAlien. Gwen grabs a mining cart so that they can all sneak past the DNAliens. Once they are away from the other DNAliens, Ben takes off the mask to return to normal and asks Gwen to use her magic to see if Max is inside the spaceship. She tells Ben that Max may have been there a couple weeks ago, but he's not there now. Kevin asks him if they should just leave then, but Ben tells him they're not finished yet. He remembers the time when Max taught him how to ride a bike when he was a kid, so he wants to finish the mission first. As they walk inside the spaceship, Kevin finds the weapons room where all the Laser Lances are kept, so Gwen uses her magic to destroy them. However, they made too much noise, and soon they are attacked by the DNAliens.
Ben uses the Omnitrix once more to transform into another new alien, Humongousaur, and he, along with Kevin and Gwen, begin attacking the DNAliens until they're all defeated. Now that the DNAliens have been defeated and the alien weapons have been destroyed, Gwen suggests that they all leave, and Ben agrees. However, before they can leave, they are confronted by a Highbreed, who orders them to get off his ship. Kevin and Gwen try to defend themselves against the Highbreed, but he is too strong. Humongousaur tells them to escape while he keeps the Highbreed busy. Gwen wants to stay and help, but Kevin grabs her and takes her outside.
The Highbreed proves to be too powerful for Humongousaur and tells him he's ruined all his plans and now has to move his ship, find a new hideout and sterilize the area by destroying all life within five miles. The Highbreed ends up throwing Humongousaur off the ship, but before he hits the ground, Gwen catches him with her magic to soften the landing. He tells them that he's going to destroy the town somehow unless he's stopped. Afterwards, the spaceship prepares to launch, so Gwen creates a magic shield to protect themselves from the blast. Before they ship can take off, Humongousaur increases his height and grabs onto the ship. As the ship reaches the city, the DNAliens controlling it inside start firing the ship's large laser cannon, destroying everything in its path.
Humongousaur sees that the cannon is headed towards a hospital, so he tries desperately to punch a hole in the side of the ship and rip out all the wires to disable the cannon. He is successful in disabling the cannon, but he ends up losing his grip on the ship and plummets to the ground below, creating a huge crater, and then turns back to normal. Due to the damage Humongousaur did, the spaceship crashes and explodes in an empty area nearby. Now that he's in his human form again, Ben realizes that the skinned knee he got while he was Humongousaur is still there in his human form, meaning any injuries he sustains while being an alien will be carried over to his human form.
Now that the DNAliens are gone, Ben wants to solve the case Max was working on so that they can find him. He thanks Kevin for all his help, but Kevin says he wants to continue helping them 'til the end, since he made a promise to Magister. Meanwhile, elsewhere, a DNAlien contacts the Highbreed Commander and tells him that Max Tennyson has continued to evade them, as well as the fact that a their supply ship was destroyed by Ben Tennyson and that he has the Omnitrix. However, the Highbreed Commander says that Ben has no idea what he's up against this time, as the camera pans out to reveal hundreds of DNAliens.