Peter Mullan proves himself a director of real bite in this harsh, affecting study of how ’60s Ireland’s strict adherence to Catholic doctrines ruined the sanity of many a young woman. If deemed to be in “moral danger”, girls were incarcerated, with nuns serving as jailers. Geraldine McEwan makes a chilling wicked witch, and a sparky cast ensures it’s an engrossing, unpreachy story.