London, 1939. As WWII breaks out across Europe, teacher Louise Fairhurst and her class are evacuated from their school to the quiet farming village of Cottlesham, Norfolk. Uprooted and forced to start her life again, Louise finds herself acting as both mother and teacher to the group of anxious ten-year-olds. Just when they begin to settle into the country and their new surroundings, tragedy strikes.

Warsaw, Poland. The German army marches closer to the capital every day, and the Polish counter-attack can only hold them off for so long. With people fleeing and the city in chaos, pilot Jan Grabowski must abandon his beloved homeland and head to Romania to fight the enemy, leaving his wife Rulka behind. When Rulka sees Poland overcome by the Nazis, living in constant danger and amid cruel reprisals, she joins the Resistance.

Back in England, Louise begins to wonder if perhaps she should have stayed in London until a chance meeting with Jan alters her path and their worlds collide forever.