The story takes place in the future. The rampant canine flu has caused the mayor (voiced by Nomura Kunichi) to issue a dog exile law, which has put all the dogs in the city on the "garbage island" and left them to fend for themselves. The mayor's guard dog Diandian (played by Liev Schreiber) is the first to bear the brunt. In this way, the dogs who were originally raised in the home with fine clothes and delicious food have become stray dogs who have to find food in the garbage dump. The leader (voiced by Bryan Cranston), the monarch (voiced by Edward Norton), the boss (voiced by Bill Murray), the duke (voiced by Jeff Goldblum) and the king (voiced by Bob Balaban) are five stray dogs on the island, and they usually act together. One day, the mayor's adopted son Atari (voiced by Koyu Rankin) suddenly landed on the island by plane, and he was going to find his lifelong friend Diandian here.