Doctor Who: The Chimes of Midnight

'Twas the night before Christmas, and all through the house not a creature was stirring... But something must be stirring. Something hidden in the shadows. Something which kills the servants of an old Edwardian mansion in the most brutal and macabre manner possible. Exactly on the chiming of the hour, every hour, as the grandfather clock ticks on towards midnight. Trapped and afraid, the Doctor and Charley are forced to play detective to murders with no motive, where even the victims don't stay dead. Time is running out. And time itself might well be the killer...