When Grandpa Max is discovered to be missing, Ben sets out with Gwen and Kevin 11 to find him. While on their search they uncover a secret weapons trade which is being held between two alien groups.

Ben, Gwen, and Kevin stow away aboard the ship of their new alien adversaries, and discover that their leader is plotting a campaign to exterminate the human vermin of Earth. Ben also discovers that the Omitrix no longer protects his human form from damage whenever his alien forms are harmed

The gang runs into a Heatblast as they search for other Plumbers who are using Grandpa Max's badge.

When Kevin meets up with an old friend, he shatters Ben and Gwen's trust when he drives away with the Rust Bucket in hopes of trading it in for value. Unfortunately, Kevin's so-called accomplice double crosses his trust. Now he must prove to his team what he was really after.

The team heads out to find more allies to join them after receiving a message from Grandpa Max. Ben is relieved to find one, although he soon learns that his charms are much more deceiving than his looks.

Ben's cousin, Ken, has gone missing. Ben insists that Kevin should help out, although he could care less until he learns that Ken is Gwen's older brother. As they look, they encounter Grandpa Max, and a shocking secret of the DNAliens.

While Ben has a date with Julie, it is soon ruined when a Galvanic Mechomorph named Ship makes trouble at the local fair. Ship is after Ben, but Ben doesn't know why. Ben needs to find out before the symbiote alien wrecks his night out.

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.

Ben steals a robotic glove from Kevin's GTO to battle the bullies, but it causes trouble instead.

A time traveling hero joins forces with the gang to battle a monster ripped straight from the 1950s.

Ben is torn between his mission and the escaped dragon he has captured from the Forever City after learning about both sides of the conflict.

Freelance young Plumbers vow to exterminate any alien they find. But soon, when they encounter Ben and the team, they mistake them as hostile aliens.

Emperor Milleous plans to destroy the planet Earth for kidnapping his daughter. In order to save the planet, Ben must uncover the secrets of Alien X.