1984. Fleeing Scotland in the wake of family disgrace, 16-year-old Ida Campbell secures a scholarship at a failing girls' boarding school on a remote part of the south English coast. Despite the eccentricities of her new Headmistress, who warns her of the dangers of the Cold War and the ever-present threat of the bomb, St Anne's seems like a refuge to Ida. But all this is about to change.