Five years after the original Ben 10 series, Ben Tennyson is a normal teenager who has put away his toys, including the Omnitrix that gave him his powers. Ben's life takes a turn when he is attacked by an alien and discovers that Brandpa Max is missing. To find his grandpa, Ben teams up with his cousin, Bwen, his grandpa's partner, Magister, and even his former nemesis, Kevin 11. When they discover the Forever Knights (a secret organization that deals in illegal alien technology) and DNAliens (the Highbreeds henchmen) are trading dangerous weapons, Ben decides to once again don the Omnitrix and he quickly learns that he can now transform into Ten New Aliens.

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.

Gwen discovers that Grandpa Max's Plumbers Badge emits a map showing the location of other Plumbers. Ben, Gwen, and Kevin follow the map to nearby town and run into a HEATBLAST. He helps the heroes discover that DNAliens have taken over the town and have erected a tower to CONTROL THE WEATHER. Ben must develop leadership skills to help a young hero save his hometown.

Ben and Gwen are finally starting to trust Kevin when Kevin steals the RUSTBUCKET and tries to swap it for some alien tech from ARGIT (an alien black market dealer)! Argit then steals the Rustbucket from Kevin and runs away. Ben and Gwen must learn to trust a flawed teammate as they help Kevin claim the important alien tech he is desperately after and face-off with one of Ben's old foes, VULKANUS.

Grandpa Max has left a message for Ben instructing him to gather a team of heroes. Ben finds a powerful new ally named MIKE MORINGSTAR but the addition of Mike to the team tests the relationships of Ben, Gwen, and Kevin. Ben learns the importance of using judgment as a leader when our group of heroes finds the truth behind a series of attacks by ZOMBIE GIRLS.

Gwen's older brother, KEN, disappears and she gets Ben and Kevin to help her track him down. Their investigation leads them to find not only Ken, but also another long-missing relative, and a startling secret of the DNAliens. This discovery comes at a high cost as Ben is left with greater responsibilities than ever before.