Inspired by a real dog from Danny & Ron's Rescue from the popular documentary, Life in the Doghouse, this fourth book in the sweet chapter book series follows a dog's rivalry with his new cat sibling. Finn, a Redbone hound with three legs, is excited to join the Figueroa family, who are also expecting a new baby to arrive any day now! The house is full of new toys and fun places to explore, but for Finn, who is still adapting to his missing back leg, the stairs are too daunting to manage. But Finn's new home holds one big surprise--a new cat sibling, Rusty, who has three legs just like him! Finn is determined to become best friends, but Rusty has other plans. And when the two start fighting over the family's attention, it turns into a battle to be the favorite pet. Will Finn and Rusty learn to get along before their new human arrives? Or is the dog-cat divide too large to cross?