The summer finally ends. Ben and Gwen have to go back to their normal lives. Grandpa Max tells Ben to keep the Omnitrix a secret from everyone, even his parents. Ben agrees, but Vilgax arrives and he'll stop at nothing to get the Omnitrix.

The Megacruiser flies solo in space, and inside Kevin examines the giant ice block found in space. Inside the mass, held Vilgax, and Kevin underestimated his current situation. He was very much alive and well, and they soon create a partnership after learning that they were both after the same person. On Earth, Ben plays around with the Omnitrix, hoping to find a better way of controlling it. Eventually, he finds the master control of the Omnitrix, giving him the ability to alternate between aliens, as well as prolong his duration with a form. Although his discovery has given him a stronger advantage, will it be enough to stop the danger that lies ahead?

Vilgax tries to get the Omnitrix for himself while Grandpa Max's strange past becomes known, causing a showdown between Vilgax and the Tennyson family.

Ben, Gwen, Cooper and Grandpa Max face their last battle ever against the villains they have encountered and they will battle to get the world's most powerful energy source.

When Gwen is abducted, Ben as XLR8 follows her abductor to the future where they discovered that her abductor is the future Gwen and they discover his future version of Ben and Grandpa Max. In the future, Dr. Animo revives Vilgax and plots to open the Null Void chamber. Both Bens must work together to stop them.

The Forever King sets his plan in motion and recruits the most powerful enemies Ben has ever faced in order to steal the world's most powerful energy source.

At a city, Ben, Gwen, and Grandpa Max are waiting outside a video game store to purchase the newly-released Sumo Slammer video game. Gwen and Grandpa Max go the book store, but when they return to check on him, Four Arms comes out of the store by force. They return to the RV, and find that Ben is already there. Gwen yells at Ben for what he's done, but he has no clue of what she's talking about. But as she gives direct evidence that Four Arms was attacking the city, Ben heads out to find the perpetrator, using the identity of his aliens to ruin his current reputation as a hero.

A terrorizing nightmare of Ghostfreak is half the trouble for an unnerved Ben, as a tour of an important academy that Gwen wishes to attend is disturbed by the uncanny alien's manifestations and the antics of Acid Breath, Frightwig, and Thumbskull.

Ben, as Wildvine, is fighting against an evil werewolf and is bitten. The Omnitrix times out and Ben turns back to his human form. Then, when the werewolf hits the Omnitrix, it starts to mess up and act weird. After all of this, Ben starts to get a crush on a girl that he meets. But things change, as Ben slowly starts to turn into a werewolf himself.

Ghostfreak's return spells disaster for our heroes. Grandpa Max and Gwen must deal with the mummy alien in space while Ben deals with Ghostfreak and Dr. Vicktor on Earth. Ghostfreak then reveals his master plan: he plans to blanket the Earth with Coronium so that sunlight will not reach the planet so that he may rule. With the power of a new alien in the watch, can Ben stop Ghostfreak, and save Grandpa and Gwen?

During a battle with Dr. Animo, the Omnitrix is accidentally set to self-destruct. In order to stop it, Ben, Gwen, and Tetrax travel across space to track down the Omnitrix's creator, Azmuth.

Ben meets a mutant who can absorb any form of energy and may be after the Omnitrix.

In the middle of nowhere, Ben, as Diamond Head, fights Kevin 11, who is still in his mutated form. As they fight, they are taken to a ship, where a battle between different aliens are held. But when a mechanical droid named Slix decides to create a bond with Ben and Kevin as a team, they immediately turn his idea down. But with no choice, they must find a way out. Will Ben and Kevin learn the importance of teamwork?

Ben is pursued by three bounty hunters sent by Vilgax to steal the Omnitrix.

While driving on a Florida highway, a bus of escaped felons rams into the RV. Ben transforms into Stinkfly (though not intentionally) and tries to stop them. With a little help from Grandpa's handy driving, and a magic spell from Gwen, the felons are put back in jail. On the news, the Tennyson's hear about purple lightning delaying a space shuttle launch. Remembering the lightning from the encounter with the werewolf and mummy aliens, they head to Cape Canaveral. At the Space Center, Ben comes under attack by the werewolf and mummy aliens, and new Frankenstein alien. However, why is the purple lightning occurring, and what ties does it have to an old "friend"?

While on a desert highway, the RV gets stolen by a group of modern-day pirates, who use it to go on a robbery.

When Ben accidentally breaks Gwen's laptop, he participates in the "Ultimate Wrestling Competition" as Four Arms to get the prize money for a new laptop to replace Gwen's broken one.

Average kid, ten year old Ben Tennyson, his Grandpa Max and his cousin Gwen's summer of adventure takes an odd turn when Ben discovers a watch like object that has been jettisoned from alien spacecraft high above the Earth.

The Tennysons stay in as it rains outside, and Ben plays a video game to pass the time by. When Gwen decides to join in, Ben is jealous of how she's a far superior player. Instead, Ben decides to transform to Upgrade, and merges with the game console. Gwen makes an attempt at shaking him off, but suddenly, a lightning strike causes them to transfer into the video game itself. The only way Ben can use the Omnitrix is to find coins with the different aliens on it. To get out, they must find the Upgrade coin before an evil being uses it to escape into the real world.

Enoch and the Forever Knights return, putting Ben in a dream world where he's tricked into having the perfect day. However, his dream quickly turns into a nightmare.

In the future, Ben gives his son, Ken, an Omnitrix for his 10th birthday. However, Ben will have to learn to trust him with that power.

Ben discovers an evil circus that's headed by a psychic vampire clown named Zombozo.

Dressed as Pilgrims, to honor their history, while in the streets of Salem, MA, Ben, Gwen, and Grandpa Max witness an explosion of a nearby building. But when Ben rushes to the rescue, Charmcaster is there waiting with a spell to take over Ben's body and the Omnitrix. Only things go awry and Gwen and Charmcaster switch bodies. Gwen goes to prison and the sorceress is brewing a plan to gain the Omnitrix. Now Gwen must find the way to get out of prison, alert her family against Charmcaster, and get her own body back using every trick up her sleeve... or Charmcaster's.

In order for Ben and Gwen to learn the value of hard work, Grandpa Max takes them to a farm. Meanwhile, an alien mummy arrives to uncover a rare and dangerous element.

While snowmobiling, two guys accidentally release an alien named Xylene from a strange container. At a park, Ben (as Wildmutt) steals Gwen's kite, so she casts a spell to make dogs attracted to him. Grandpa Max seems sad to be in St. Louis since it is where he met his wife. Xylene attacks, and Grandpa Max comes to defend, only to recognize her. Xylene reveals that she came to find the Omnitrix since she lost it when Vilgax attacked her ship. While Grandpa Max and Xylene talk about the past, a robot emerges from the area where Xylene was and attacks Ben and Gwen. The mechadroid attacks twice, taking Grandpa Max with him. Now Ben must work with Xylene (to his dismay) to save Grandpa Max.