When the Flatbottoms rushed to the hospital on the night of their baby's birth, they never expected the apple to fall so far from the tree. Their newborn's enormous butt is as hard as steel and packed with an array of explosive farts that can defeat any adversary. His superpowers have also attracted the attention of a crazed, evil doctor, who relentlessly seeks to discover the secret behind his ultra-powerful butt.

With a wild doctor pursuing him, this walking, talking newborn - known as Agent Big Butt - has to navigate the life of a superhero while dealing with newfound fame, going to school, making friends and defeating bullies, all before his first birthday.