October 1944: Seeing that World Battle II attracts towards its conclusion, a Nazi defeat begins to appear almost inevitable. But that could be about to switch… Two intruders are captured in the grounds of Colditz Castle, the most secure POW camp in Germany. At first, the guards think they’re dealing with British spies. But the strangers arrived in an advanced exploring machine, the like of which they’ve never seen before. With this TARDIS within their hands, the Third Reich might triumph in the end.