Arnold Walkers decision to take early retirement and become caretaker and part-time tourist guide at a Tudor mansion changes his life dramatically. His wife Mildred leaves him and his wayward daughter Flora arrives unexpectedly and agrees to help out. A once widely acclaimed expert of the Tudor period and former curator of Emerton Hall, Sir Henry Penrose at 90 suffers from senile dementia and unless tranquilised is subject to spontaneous acting out of bizarre historical events. Flora then befriends him and causes havoc at the Hall when she allows him to roam around the estate in the firm belief that the mad are entitled to as much freedom as the sane! So when Sir Henry is found dead in the dungeon, is it an accident or… murder?