Princess Margaret learned a shocking family secret before returning to the sidelines.
The Queen’s sister, Princess Margaret (Helena Bonham Carter), was largely pushed to the periphery of season four — except for episode seven, “The Hereditary Principle.”
Margaret requested more royal duties from the Queen but was instead told that her role as Counsellor of the State would be given to Prince Edward (Angus Imrie).
Driven into a depression by a health scare and her loss of duty, Margaret sought help.
To her surprise, her new therapist (Gemma Jones) informed her that there was a history of mental-health issues in the royal family and that she had two cousins, Katherine and Nerissa Bowes-Lyon, residing in an asylum.
Although public records showed that the sisters were dead, a confrontation with the Queen Mother (Marion Bailey) exposed that they were sent away because of developmental disabilities caused by inbreeding in the bloodline.
Pressured to keep quiet, Margaret kept her royal title and returned to her life of entertaining on her private island of Mustique.