In Dog Man 5: Lord of the Fleas, a new group of villains called the Fleas attacks the city using a giant robot to get revenge on Petey.
Dog Man, Cat Kid (Li’l Petey), and their friends must work together to stop them. Meanwhile, Petey tries to change and become better because of his son’s kindness and influence.
In the end, the heroes defeat the Fleas by shrinking them and save the city. Petey continues to improve, showing that people can change, while Li’l Petey represents kindness and hope.