Dav Pilkey's Captain Underpants returns in full color, and this time it's snot pretty! Pass the tissues, please! George and Harold are up to their old tricks again, and when their latest prank makes a direct hit on school brainiac Melvin Sneedly, he decides to get even! But in the blink of an eye -- and the sneeze of a nose -- Melvin goes from snooty to snotty, and the Bionic Booger Boy is born! Can Captain Underpants clean up this catastrophe, or will the mucous monster make a mess of things?