Matthew Stroud wants nothing more than to live a normal life, but that's easier said than done with cat ears on his head and a cat tail attached to his lower back. Only two people know he's a cat boy: one is his best friend and fellow monster boy, Mark Koenigsegg, and the other is Mark's human mother, Ashley Koenigsegg. Shortly after starting high school, Matthew develops a crush on Emily Thompson, a human who worms her way into his tiny friend group. She quickly senses something's wrong with her new friends, from their secretive behavior to their animallike appearances, especially when they befriend another boy, John Woodcock, who seems oddly unbothered by everything weird about them. As her suspicions deepen, Matthew must do everything in his power to keep Emily off of his scent, even as he continues to fall for her, because everything will fall apart if she learns the truth.