Dog Man, a crimefighter with the head of a police dog and the body of a policeman, faces off against his archnemesis Petey the cat. Dog Man, the newest hero from the creator of Captain Underpants, is still learning a few tricks of the trade. If only the Chief would throw him a bone every once and a while ... Dog Man needs to dry up the drool, dust away the dander, and roll out of the refuse if he's going to impress the Chief, and he needs to do it...

George and Harold create a new comic book hero in Dog Man, a crimefighter with the head of a police dog and the body of a policeman, who faces off against his archnemesis Petey the cat.

George, Harold, Captain Underpants, and Sulu the bionic hamster battle the three ridiculous Robo-Boogers in an attempt to turn the Bionic Booger Boy back into Melvin Sneedly.

Dog Man has been working hard to overcome his bad habits, but when his obsessions turn to fears, he finds himself the target of an all-new supervillain, while Petey the Cat, who was just released from jail, starts a new life with Li'l Petey.

When George and Harold hypnotize their principal into thinking that he is the superhero Captain Underpants, he leads them to the lair of the nefarious Dr. Diaper, where they must defeat his evil robot henchmen.