When Grandpa Max’s engineer buddy Phil Billings gifts Team Tennyson the Omni-Copter, a state of the art flying 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: the Forever Knight.

During one last stop by a toy store before Ben, Gwen, and Grandpa Max's maiden voyage across the Atlantic, Ben runs into an old bully, Kevin 11, who now has new powers. He's able to transform into aliens just like Ben, such as the "bootleg" doppelganger of Cannon-bolt—Wrecking-bolt!

Back stateside, Ben can't get into a cat cosplay competition, Top Tail, without a cat costume of his own; but when he goes Rath, a new cat-like alien with an attitude, Ben's newfound wild side quickly becomes much more than he bargained for, and must learn to hold in his rage.

When Ben, Gwen, and Max try to travel to the South Pole, magnetic disturbances cause the instruments to malfunction and take them to the North Pole instead, where they find that two criminal scientist brothers, Polar and Solar Twain, have plans to swap the magnetic poles of the Earth, unleashing technologic and atmospheric disturbance unless the world pays a ransom.

Ben, Gwen, and Grandpa Max arrive at a Native American park to see the Ayasha Plinths, an ancient Stonehenge-like rock formation. But when Hex arrives, he casts a spell that causes everyone to interpret what he says as a lie, turning Hex into a hero planning on creating the Golem of Ayasha.

During medieval times, Team Tennyson must fight to remember that they're not in the past at all, but actually at a Renaissance-ques fair, where Zombozo has hypnotized its guests into thinking they live in the past.

After an overpass collapses on the highway, Team Tennyson is trapped in a traffic jam along with Simon Sez and his family. But when Ben and Simon team up to tackle the gridlock together, Simon only makes matters worse.

After traveling to Tampa Beach, Florida, Team Tennyson hopes to get some much-needed rest & relaxation, but the Weatherheads have other plans that Ben must thwart: a solar powered tower so that they never worry about losing power.

During a family cookout at a forest campsite, Charmcaster uses her magic to switch places with Gwen, but when Ben catches "Charmcaster" sneaking about, he attacks, unaware it's actually his cursed cousin.

In Aspen, Colorado, Ben, Gwen, and Grandpa Max are on a hike to find the Forgeti, but when they realize they've stumbled upon Billy Billions own "Winter in July" ski resort, Ben must battle Billy, with an assist from the Forgeti itself.

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. Not only does this cause the Rustbuggy to mutate into a metallic monster, but it makes Glitch become a speed demon who kidnaps Gwen!

Team Tennyson wonders what the Bugg Brothers are up to when the group runs into them while vacationing at the Chrysalen Institute.

After a battle with Kevin gets cut short, Ben turns his attention to one-upping Gwen at Space Camp. But, when Kevin returns with his sights strangely set on his cousin, our hero discovers who is really behind it all: Charmcaster!

When attacked in the jungle, Team Tennyson is saved by a toddler who looks eerily similar to Tim Buktu, but when they discover it really a pint sized version of the nefarious globetrotter, Ben knows there's another threat looming: Nanny Nightmare.

Team Tennyson discovers a Hartfield-McJoy (a parody of the Hatfield-McCoy feud) reenactment in the cornfield next door, but when Hex resurrects the ghosts of the real feuding families, Ben must find a way to bring them together in order to save the day.

While Phil and Grandpa Max tune-up the Omni-Copter, Ben takes the Rustbuggy off road, but when he is suddenly captured by Tetrax, our hero must not only escape but avoid the wrath of the double-crossed Kraab and Sixsix!

Team Tennyson discovers that a small village's goats are being terrorized by the legendary Chupacabra, but when Ben realizes it's actually Dr. Animo, our hero must thwart the dastardly doctor.

After winning a Sumo Slammers Champion belt, Ben returns to the Rustbucket to find it in the arms of Kevin, but when his rival hijacks the Rustbuggy instead, our hero must stop at nothing to get back what belongs to him. Eventually, though, Kevin and Ben must work together to fend off an attack from the Forever Knight, who is angered at Kevin's refusal to follow orders.

At a local swap meet, Ben instead sets his sights on a Sumo Slammer collectible, but when Kevin takes it for himself, our hero must get it back by overcoming Kevin's secret weapon: an 11th alien named Bashmouth.

During their visit to the Twin City, Ben and Gwen sign up for some Laser Town awesomeness, but when Ben is teamed up with Kevin, the two must overcome their differences if they are to end up on top, especially since Gwen has been paired with the mysterious Fang. 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 in order to change back.

When Team Tennyson's trip takes them to Scotland, they plan on visiting the various locales of Scotland, but their plans are foiled when the Fogg returns to exact its revenge.

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. However, it turns out that Kevin Levin has followed them to Britain, and showcases three new alien forms based on those Ben has lost: Thornblade (Wildvine), Undertow (Overflow), and Dark Matter (Grey Matter).

When Ben and the others take a trip to Paris, Ben, impatient and uninterested, accidentally gets himself locked out of the Omni-Copter. To make things worse, he can't communicate with the people of France, and Ben ends up in the clutches of Zombozo, who hypnotizes him into being unable to speak.

Team Tennyson checks out a Samurai Museum in Tokyo. However, Ben finally comes face-to-face with the Forever Knight when he steals a valuable sword from the museum and starts a chase across the rooftops.

Tim Buktu returns, seemingly reformed after saving people from a dragon in the streets of Tokyo. But the Tennysons suspect there's more to Tim's actions than meets the eye.