The episode is set on Christmas Eve, 1860. The Doctor and Amy Pond arrive in a small Welsh village, where ghostly apparitions have been seen. They soon discover that these ghosts are actually Gelth, deceased beings from a planet near a dying star. The Gelth are trying to communicate with the living but are misunderstood and feared. The Doctor and Amy befriend a local named Gwen, who can see and interact with the Gelth, and together they unravel a mystery involving a medium, a conspiracy, and a chance to help the Gelth find peace.