Ben 10: Alien Force
Ben 10 Returns, Pt. 2
S1 E2:
After defeating the Forever Knights, Ben, Gwen, and Kevin follow a lead that takes them to a secret base in the desert. There they hope to find their missing Grandpa but instead find a spaceship with a giant cannon. The Highbreed (our shows overall villain ? a group of racial supremacists) intend to use it to Destroy a nearby city. The trio of heroes is able to stop the ship and afterward they decide to team up for good in order find the missing Grandpa Max and unveil the secret alien plot of the Highbreed.