A Nun's Story by Sister Agatha with Richard Newman
Shirley Leach gave up a life of luxury and privilege for a life of poverty, chastity and obedience as Sister Agatha - but, for example, counting Paul Getty as a friend and having him fund the development programme of the convent you head still sounds pretty privileged to me and it's a strange sort of poverty that includes holidays, retreats, lecture tours and such like in foreign countries . . . . I feel this has raised rather more questions than it's answered!
My next nonfiction for this Challenge is Queens of the Conquest by Alison Weir, the hefty first book of a planned four volume history of England's medieval queens from 1066 to 1485, starting with Matilda of Flanders, wife of William the Bastard, and ending with Anne Neville, Richard III's queen.