In this charming animated tale, an unlikely friendship forms. Deep below snowy, cobblestone streets, tucked away in networks of winding tunnels, lives a civilization of hardworking mice. These mice are terrified of the bears who live above ground. One special mice, Celestine, is an artist and a dreamer. She nearly ends up as breakfast for the bear Ernest, and the two form an unlikely bond. But it isn’t long before their friendship is put on trial by their respective bear-fearing and mice-eating communities.