An eleventh Doctor adventure, featuring the Doctor as played by Matt Smith and his companions Amy and Rory. The winter festival is approaching for the hardy colony of Morphans, but no one is in the mood to celebrate. They're trying to build a new life on a cold new world, but each year gets harder and harder. It's almost as if some dark force is working against them. Then three mysterious travelers arrive out of the midwinter night, one of them claiming to be a doctor. Are they bringing the gift of salvation or doom? And what else might be lurking out there, about to wake up?

After thousands of years of expansion and conquest, the human Imperium is at its height. His dream for humanity accomplished, the Emperor hands over the reins of power to his Warmaster, Horus, and heads back to Terra. But is Horus strong enough to control his fellow commanders and continue the Emperor's grand design?