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? When the Doctor’s shadow is sacrificed by villagers, he brushes it off as medieval superstition - until he begins to grow weak. Can he uncover the truth behind the bridge master’s curse before it’s too late?