[1][2] Ben Tennyson is tasked with cleaning the Rust Bucket, but when he is tricked into letting Sid and Maurice steal it, he must chase them down before they create an unstoppable maggot monster with the intention of holding Las Vegas for ransom.
While visiting a monastery with a no-noise policy, Ben accidentally awakens a dangerous dragon hidden in a secret chamber below the hallowed halls.
Ben is captured by a gang of superior mutants called the Alphas, who lock him inside the secret lab of their mad scientist Doctor Animo, and must help the lesser animals, the Accidentals, escape while stuck as Stinkfly.
Part One: Ben's trip to Portland with his family is interrupted by the arrival of a brand new, eleventh alien, Gax, as he fights another one of Doctor Animo's monsters.
It premiered on: On a visit to Cape Canaveral, the Tennyson Trio attend the launch of an experimental space plane, but when Vilgax hijacks the ship, Ben must stop him from weaponizing the shuttle.
Aboard the SS Pettigrew, on its maiden voyage, Ben must not only battle seasickness, but Steam Smythe, who looks to use his mechanical creatures to sink the steamship's replacement.
During a routine trip to the DMV, Max takes a driving test to renew his license, but Zombozo hijacks the role of instructor, bent on revenge against Ben.
As the Tennyson trio dig up dinosaur fossils in the Badlands National Park, Ben is unaware that Vilgax and Doctor Animo have teamed up to steal alien DNA from within the Omnitrix.
Part Four: Mind Over Alien Matter: While inside the Omnitrix, Ben and Vilgax must work together if they are to close the gateway, but once the Fulmini leader - the High Override - appears, even that might not be enough.
When Grandpa Max's engineer buddy Phil Billings gifts Team Tennyson the Omni-Copter, a vehicle that can transport the Rustbucket for overseas adventures, Steam Smythe takes to the skies to ground Ben and company's first test flight; but unbeknownst to our heroes, Smythe was sent to battle Ben's latest alien forms by a mysterious, powerful enemy.
Ben and Gwen's recreational drive in the Rustbuggy takes a turn when Glitch bonds with part of Kevin 11's version of 'Upgrade' named Bootleg.
To make things worse, a hit from a laser causes Kevin to be trapped in the form of his version of Four Arms named "Quad Smack", and he needs to find a way to fix his Antitrix to change back.
Team Tennyson finds out about their British ancestry, so they visit their relative's estate, but mysterious events convince Ben that the place is haunted.
Part One: Pyramid Scheme: While the Tennysons visit Chichen Itza, Dr. Animo fuses a chicken and a snake to create a real life quetzalcoatl.
The Tennysons find themselves stuck inside an inescapable funhouse constructed by Zombozo; Ben goes alien and fights to escape, ultimately proving that behind every illusion, there's a disappointing secret.
Ben and Gwen learn a rumor of an alien invasion happening at the park they are camping at, but when they investigate, they discover a preserve containing a host of mutated creatures engineered by Animo.
While Grandpa Max struggles to keep pace with an unbelievably fit rival, Ben and Gwen run into the Weatherheads, who have secretly masterminded the race to test mankind!
In the distant future, an alien race called the Xerge comes to Earth to invade the entire world forcing President Gwen Tennyson to recruit her long-lost cousin, a disillusioned Ben 10,000.