Deep below snowy, cobblestone streets, tucked away in networks of winding subterranean tunnels, lives a civilization of hardworking mice, terrified of the bears who live above ground. Unlike her fellow mice, Celestine is an artist and a dreamer—and when she nearly ends up as breakfast for ursine troubadour Ernest, 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.