The year is 1940, Britain. With the nation devastated by the war, the British ministry turns to propaganda films to boost morale at home. Realizing their films could use "a woman's touch", the ministry hires Catrin Cole (Gemma Arterton) as a scriptwriter in charge of writing the female dialogue. Although her artist husband looks down on her job, Catrin's natural flair quickly gets her noticed by charming lead scriptwriter Buckley (Sam Claflin). Catrin and Buckley set out to make an epic feature film based on the Battle of Dunkirk starring pretentious fading movie star Ambrose Hilliard (Bill Nighy). As bombs are dropping all around them, Catrin, Buckley and their colorful cast and crew work furiously to make a film that will warm the hearts of the nation.