Count Grendel of Gracht wanted the throne, and he wanted to become the legal and rightful King, and was expected to make a move during Reynart's coronation. To protect himself, Reynart had an android duplicate of himself built. Grendel kidnapped the prince so that he could not be crowned.
If he did not show up at the ceremony, Grendel would be crowned instead of Reynart. The Fourth Doctor, Farrah and Zadek used the android in Reynart's place so that he would still be crowned. Reynart was joined in his cell by Romana I, who tended to his injuries which he had suffered during his captivity. Later Grendel came up with a fresh plan to have Reynart marry Romana, who looked like Princess Strella, which would make Romana the Queen. Grendel planned to have Reynart killed, and then marry Romana afterwards and then kill her in turn. His plan was foiled by the Doctor. Reynart was released after the count's defeat. (TV: The Androids of Tara)