The second installment in the main Ben 10 series. It premiered on Cartoon Network USA on April 18, 2008, with the final episode airing on March 26, 2010. The entire series consists of three seasons with a total of 46 episodes. This installment was planned to have 46 episodes from the production stage and was originally intended to be titled "Ben 10: Hero Generation." "Ben 10: Alien Force" is set five years after the events of "Ben 10." Five years have passed since the events of "Ben 10," and Ben and Gwen have become middle school students. Ben has long stopped wearing the Omnitrix and has been living an ordinary life, even becoming the goalkeeper for his soccer team. Just as he is about to show his MVP medal to Grandpa Max, he discovers that his grandfather has gone missing. He finds Gwen and puts the Omnitrix back on to investigate. As the investigation deepens, they uncover a plot by the Highbreed to invade Earth. The core team is missing Max, but their former enemy Kevin joins as a new ally. In addition to Ben reactivating the Omnitrix, Gwen and Kevin's abilities also undergo changes and grow stronger as the story progresses. Furthermore, descendants of the Plumbers with alien superpowers begin to appear. With everyone's help, Ben successfully convinces the Highbreed to cancel their invasion. Meanwhile, Vilgax launches invasions across the universe and seeks revenge on Ben. Ben attempts to hack the Omnitrix, but this causes Kevin to mutate under the influence of the Omnitrix's energy. Although they defeat Vilgax and protect Earth, Vilgax's ambitions are far from over. In the end, after defeating Vilgax, he is severely injured. The Omnitrix is destroyed, Kevin returns to normal, and Ben's transformation device is replaced by the Ultimatrix. Compared to the previous installment, this series has a tighter narrative structure with overarching goals driving the story. The main antagonists in the first and second seasons are the invading Highbreed and their hybrid subordinates, while the third season focuses on Vilgax. The Forever Knights also appear in this series, but their influence is relatively lower compared to before, and they have less screen time than the Highbreed and Vilgax. The tone of the story is more serious than the previous installment, particularly Ben's personality in the first two seasons. The main story missions in the first and second seasons are related to the Highbreed, with important character relationships including Ben and Julie's romance and Gwen and Kevin's relationship. The third season's missions primarily revolve around Vilgax's ambitions, and Gwen and Kevin's relationship is challenged due to Kevin's mutation.