It is 1940. France has fallen, and only a narrow strip of sea lies between Great Britain and invasion. The war could go either way, and everyone must do their bit. Young copywriter Catrin Cole is drafted into the Ministry of Information to help write women into propaganda films - something that the men aren't very good at.

She is quickly seconded to the ministry's latest endeavor: a heartwarming tale of bravery and rescue at Dunkirk. It's all completely fabricated, of course, but what does that matter when the nation's morale is at stake? Since call-up has stripped the industry of its brightest and best, it is the callow, the jaded, and the utterly unsuitable who must make up the numbers: Ambrose Hilliard, third most popular British film star of 1924; Edith Beadmore, Madame Tussauds wardrobe assistant turned costumier; and Arthur Frith, whose peacetime job as a catering manager has not really prepared him for his sudden, unexpected elevation to special military advisor.

Now in a serious world, in a nation under siege, they must all swallow their mutual distaste, ill will, and mistrust to unite for the common good, for king and country and - in one case - for better or worse.