Ben discovers that the Forever Knights are trading weapons with the DNAliens, while at the same time, Grandpa Max has mysteriously gone missing. He decides to return the Omnitrix on his wrist and go hero once again.
Five years later, 15-year-old Ben Tennyson chooses to once again put on the Omnitrix and discovers that it has recalibrated and can now transform him into 10 brand new aliens. Joined by his super-powered cousin Gwen Tennyson and his equally powerful former enemy Kevin Levin, Ben is on a mission to find his missing Grandpa Max. In order to save his Grandpa, Ben must defeat the evil DNAliens, a powerful alien race intent on destroying the galaxy, starting with planet Earth.
Ben discovers that the Forever Knights are trading weapons with the DNAliens, while at the same time, Grandpa Max has mysteriously gone missing. He decides to return the Omnitrix on his wrist and go hero once again.
Ben, Gwen, and Kevin follow a lead that takes them to a secret base in the desert. There they hope to find Grandpa Max but instead find a Highbreed spaceship with a giant cannon.
Gwen discovers that Grandpa Max's badge is able to signal other Plumbers. However, by using it, they meet up with a familiar face, a pyronite.
Kevin shatters Ben and Gwen's trust when he steals the Rust Bucket to sell for alien technology on the black market.
Grandpa Max leaves Ben a series of instructions to contact a team of heroes. Things go the wrong direction when they soon find them.
Gwen's older brother, Ken, is suddenly missing. As they look, they encounter a surprise leading to a shocking secret from the DNAliens.
While Ben has a date with Julie, it is soon ruined when an alien named Ship makes trouble at the local fair.
When Ben and Gwen learn that their grandmother Verdona is an alien being, Verdona insists that Gwen should come along with her to her home planet and improve her abilities. With this, Gwen is faced with a difficult decision between a human and alien life.
When Ben stands up to Cash and JT, they soon discover a robotic gauntlet from Kevin's vehicle. With it, Cash decides to get back on Ben, although this time, it's more than just a joke.
A time experiment in the 1950s sends a bizarre monster to Ben's time. Now Ben, Gwen, and Kevin must team up with Paradox, a time traveling hero, to face off against the unstoppable creature.
The Forever Knights secure a weapon in hopes of aiding them slay a dragon they have held captive.
Freelance young Plumbers mistake Ben and his team as a threat.
An alien emperor plans to destroy the planet Earth for kidnapping his daughter. In order to save the planet, Ben must uncover the secrets of Alien X.
