It’s the deepest part of winter, the exact midpoint, Christmas Eve – half way out of the dark. Amy and Rory are trapped on a stricken space liner that’s plummeting through banks of thick icy fog to the surface of the planet below. Only one man has the power to save them; only one man is in possession of a machine that can clear the fog and let them land safely. That man is Kazran Sardick, a rich but lonely old miser who rules Sardicktown with a sky-mast of iron. The Doctor’s only chance of rescuing the ship ...