Separated from his companions, the Doctor attempts to find solace in the history of his favourite planet – Earth – but instead discovers new threats lying in wait. Travelling from twentieth-century East Berlin to sixteenth-century Strasbourg, the Doctor encounters creatures from other realities: monsters beneath the waves, and human beings determined to exploit their fellow man. But how long can he survive without a friend? Arriving in Strasbourg at the height of the Dancing Plague, the Doctor finds himself thrust into a world of paranoia. Can he bring peace to a city at odds with its own people?