Before the war, life is easy for Irish-born Louise O'Brien. She is part of a small family of nuns, happily working together and living in the grand old convent in Ypres, serving the poor. When the Nazis claim ownership of the buildings, she joins the Maquis Resistance fighters, working as a nurse in a field hospital. That's where she first meets Jacko, an injured Australian airman.
After the war is over, she returns to her religious Order and accepts a new post in Giverny, Ireland. The convent is controlled by the narcissistic Mother Superior, Sister Michaela. When Louise refuses to bow to her superior's commands, she is physically abused by Michaela, who then allows three men to sexually assault her. Louise's complaint is dismissed by her bishop, who opts to transfer her to a convent in Sydney, Australia. After Jacko successfully pursues justice against Michaela and the bishop, they are directed by The Pope himself to give up their vows and return to civilian life.
Michaela unleashes a war of revenge that sees her chase Louise all the way to Australia. As in any war, there are casualties along the way.