Mouse lives in Dogtown, a shelter for real dogs and robot dogs, where the kibble is plentiful, and the rafters hide a secret community of mice. His unlikely best friend is Buster, a big-hearted real dog who attracts trouble like a burr to fur.Determined to help Buster find his forever home, even if means losing his best pal, Mouse embarks on a bold quest with three of Dogtown's 'unadoptables' Buster, Stewie – a huge, lovable dog whose ex-owner said he was mean, and Smokey – a robot dog hardwired with a smoke alarm he can't control.But Mouse is just a mouse, and the world is big and complicated. How's a little guy supposed to find homes for the dogs he loves?