On a trip to bustling Go City, a bird themed villain named Aviarius attacks the Bueno Nacho Ron and Kim are visiting, and Kim inadvertently gains super-strength when she attempts to foil the villain in stealing a mysterious masked hero's powers. The two teens quickly find themselves involved with the retired superhero group, Team Go, who, Kim quickly learns, are Shego's family. But with everyone but Kim powerless against Aviarius and the team's two youngest members captured, they must enlist the help of Shego.