Season 09, Episode 05 – “The Girl Who Died (1)”
In a backwater of history, in a little Viking village where all the warriors have just been slaughtered, a young girl called Ashildr is about to make a desperate mistake. The Mire are the deadliest mercenaries in the galaxy, famed for being unstoppable and without mercy – and Ashildr has just declared war on them. The Doctor and Clara have twelve hours, to turn a handful of farmers and blacksmiths into a fighting force ready to face down Odin himself. And there’s more – because this is the day when the Doctor remembers where he’s seen his own face before.