It is the summer of 1938 and Phyllis Forrester has returned to England after years abroad. Moving into her sister's grand country house, she soon finds herself entangled in a new world of idealistic beliefs and seemingly innocent friendships. Fevered talk of another war infiltrates their small, privileged circle, giving way to a thrilling solution: a great and charismatic leader, who will restore England to its former glory.

At a party hosted by her new friends, Phyllis lets down her guard for a single moment, with devastating consequences. Years later, Phyllis, alone and embittered, recounts the dramatic events which led to her imprisonment and changed the course of her life forever.