The episode starts at a city, where the Tennysons wait in a long line to buy a newly released game, a game that Ben refers to as Sumo Slammer 2.1. Gwen infers that he has the game, but he explains that it's version 2.1, and that there is a big difference. Gwen can't wait any longer, and insists that they should go somewhere cool from the heat. So, they decide to enter a nearby bookstore. Later, as they come back out of the store, Gwen wonders how Ben's doing after waiting for so long. The line is no longer there, but Four Arms comes out, and he causes rampage with the police. Gwen and Grandpa Max are shocked, as they interpret that Ben is the one to blame. The SACT arrive, and prepare to capture Four Arms. Before doing so, Gwen runs up to him, and tries to stop him. With no luck, he continues and ends up being shot by the SACT. Unfortunately, Four Arms leaps off, and leaves them behind.
At the RV, Gwen is infuriated by Ben's recent actions over a video game. Ben appears to be calm and quiet as he plays his new game. While Gwen interrogates Ben, he says that he has been at the RV the whole time. Gwen tries to take the information out of him by showing him a clip of Four Arms destroying the city as evidence. Grandpa Max seems to be on Ben's side, though Gwen has a good point. So, Ben tries to prove her wrong by going out to the city to find clues to solve the mystery.
Ben spots Four Arms in an alleyway, and he goes after him. He attempts to activate the Omnitrix to transform into XLR8, though no luck. Ben finds Four Arms at the top of the US Mint building, and Ben decides to go after him. Inside, Gwen and Grandpa Max seem to find Ben anywhere, but they soon find Heat Blast attacking the place. Gwen heads to him and insists that he should stop what he's doing. Heat Blast doesn't seem to be listening to her order. Out of nowhere, Ben appears in front of Grandpa Max behind her. She then realizes that Ben is telling the truth about the alien whose impersonating his alien forms. Heat Blast attempts to attack back, but Diamond Head appears just in time to protect her.
Diamond Head prepares to fight Heat Blast, but he is stopped by coins that were held in a large container above him. As Heat Blast arrives before him, he reveals his true identity. It was Kevin, the teenage sociopath who Ben has met before. This time, Kevin seems to have mastered morphing into a perfect copy that of Ben's original forms, and Kevin has been using them to ruin Ben's reputation as a hero.
Kevin transforms into Stinkfly, and flies away, leaving Ben behind with the authorities. Diamond Head tries to explain that he is not the one responsible for such actions. They don't seem to believe him, and Gwen comes by to back his story up. So Ben has no other choice but to fight. As he runs off, Diamond Head looks for an area to hide. To soldiers find him, and shoot him, but Diamond Head counters back by knocking the platform down. As Diamond Head continues to find a way out, he is again detected, but this time, he is trapped between. To make matters worse, the Omnitrix is about to lose power. As he brainstorms for an idea, he jumps down, and he transforms back to normal just in time. He fakes an act by appearing to protect himself from Diamond Head.
As Ben returns back to Gwen and Grandpa Max, Gwen is relived to see Ben again. The SACT leader, Steel, somehow is suspicious of Ben's watch, though he lets them through, but orders his troops to follow them, just in case. In the RV, they discuss with each other with what's happened so far. Gwen finds news headlines on the Internet, and it seems that Kevin has been busy using Ben's alien forms to wreak havoc in major cities.
All of a sudden, a trolley train is shown heading down the street, and Ben decides to help out. It seems to appear that Kevin is using Upgrade to take control of the car. As Ben tries to transforms into Upgrade, he changes into Wildmutt instead, but there is no other choice but to use what he has now. As Wildmutt runs to the rescue, it seems that the SACT has also been tracking them.
Inside the car, the driver tries to stop the car, but Kevin pulls it out, which makes their situation worse. Wildmutt is behind them, and eventually gets on top of the car. Kevin finds him, and tries to get him off, though Wildmutt was able to get inside the car. Behind the car, Grandpa Max pilots the RV, transformed into its aerodynamic form. Inside the car, Kevin was able to get Wildmutt down, and he tries to get away with it by leaving and flying off with Stinkfly. The car continues to move, and it is headed to a nearby pier. Grandpa Max gets close enough and tells Ben to get on the RV to throw a grappling hook to put on the car. Grandpa Max did all he could do to brake the movements. Before the car fell to its doom, Grandpa Max and Wildmutt were able to save everyone inside it.
Later at night, the RV stops in a parking lot, and Grandpa Max and Gwen come out. It seems that they were there to pick Ben up after the incident. In an unfortunate situation, the SACT was there to take the Tennyson family down, after seeing that they were involved with the alien business. The leader continues to be suspicious of the Omnitrix, but before doing anything else, they receive a report that there is a crystal alien on the loose. The Tennysons get away at this time, though he says he's not over with them yet.
While Lieutenant Steel gets down to the bridge to deal with Kevin, he's no match for him, and he beats him up. Four Arms was there in time to save him. As he begins to fight Kevin, the SACT readies their weapon. Gwen says that they should not, because it might hit her cousin also. Steel gives an order to his troops not to shoot until on his command. As Diamond Head is no match for Four Arms' strength, he turns into Heat Blast, which he was able to have a slight advantage. However, Four Arms was able to knock him into the air, but he turns into Stinkfly. Before Stinkfly was able to attack Four Arms, he transforms back into Kevin. Four Arms comes up to him, readying a punch, though Ben did not want to destroy him. He says that he was not worth it, and he never was. With that, Kevin somehow felt something, and he immediately transformed into a freak, a mixture of the different aliens. This time, Kevin had the advantage, but Steel commands his men to shoot Kevin. With this, they successfully take him down, and he falls from the top of the bridge, down to the deep ocean water. Steel realizes that Four Arms is not an enemy, and Four Arms leaves him behind.
As the Tennysons drive off to their next destination, Lieutenant Steel stops them to have a talk with them. He wonders why aliens show up all of a sudden when they are there, but he lets them go. As they drive off, Kevin's status is unknown, as the dark ocean shows a small area where he fell.