Dog Man 4: Dog Man and Cat Kid by Dav Pilkey

When darkness falls upon the city, only one heroic duo has the pedigree to deliver justice! Dog Man, the newest hero from the creator of Captain Underpants, is back and this time he's not alone. The heroic hound with a nose for justice now has a sidekick in the form of a super-cute kitten, and together they have a mysterious caper to sniff out!