Mech pilot Lieutenant Marie Stahlbaum wants to be out stalking the stars, taking the fight to the rat-like alien verrater that destroyed her homeworld. Serving now with the famed Colonel Drosselmeier, she thought she'd finally get that chance. Instead she's stuck on guard duty, watching over a spoiled lord and his holiday merriment on the winter moon of Bavaria. When an verrater invasion crashes the party on Christmas Eve, Marie finds herself on a terrible new front line. With only a malfunctioning mech, nicknamed the "Nutcracker", and its former pilot on the radio, Marie sets off on a desperate hunt, pursuing the monstrous king of the verrater horde across the snowy wastes. But the history between the verrater and Colonel Drosselmeier is darker, and deeper, than anyone could imagine. And if Marie can't find a way to defeat the verrater king here, tonight, the whole of human space will fall.