Count Grendel is plotting to seize the Taran throne from the rightful heir, Prince Reynart, and has mistaken Romana for an android duplicate of the Prince's betrothed, Princess Strella, to whom she bears a remarkable resemblance. 

The Doctor is meanwhile captured by Prince Reynart's men Zadek and Farrah and taken to his hunting lodge, where he is forced to repair an android double of the Prince to act as a decoy for potential assassins.