Blue snow falls from the sky, freezing everything it touches. In a world that has long forgotten warmth, a teenage boy named Sunwoo Seo struggles to survive. His prosthetic leg makes it even harder to walk in the deep snow, but he trudges on southward to keep a promise he made with a young girl he tragically couldn't save. Apart from her frozen body he carries on his back, Sunwoo is all alone, until he is joined by a stranger with an oddly cheerful demeanor...and a bloody shovel in his hand.