New York, 1937: When estranged sisters Clara and Madeleine Sommers learn their grandmother is dying, they agree to fulfill her last wish: to travel across Europe - together. They are to deliver three letters, in which Violet will say good-bye to those she hasn’t seen since traveling to Europe 40 years earlier. Clara, ever-dutiful, sees the trip as an inconvenient detour before her wedding to millionaire Charles Hancock, but it’s also a chance to embrace her love of art. Budding journalist Madeleine relishes the opportunity to develop her ambitions....

Billeted together in the attic of Latimer House - a place where secrets abound - Evelyn, Betty and Judith soon form a bond of friendship that carries them through the war. Because nothing is stronger than women united. Tucked away in the Buckinghamshire countryside, Latimer House, a grand country estate, stands proudly - a witness to some of greatest secrets of WW2.

Paris, 1944: The war is nearly over, but for members of the Resistance in occupied France, it is more dangerous than ever before. Twenty-five-year-old Gabby Foucher loathes the Nazis, though as the concierge of 10 rue Royale, she does her best to avoid conflict - unlike her bolder sister Yvette, who finds trouble at every turn. 

When an impossibly shy young woman named Judy Morgan finishes her studies in Physics at Cambridge University, it is with dreams of changing the world for the better. Meanwhile, a beautiful, young Jewish woman decides to flee her beloved Austria, changing her name to Hedy Lamarr, and risking everything to get to America, as far away from the Nazi threat as possible.   

Present day, London: When Sophie discovers a photograph of her great aunt Vivi from World War II, it throws her into a world of confusion. Because, as she learns about this secret relative, she quickly realizes that the photograph doesn’t fit with her family’s story. It shows Vivi leaving an address associated with a spy network in London - a place she had no reason to be - and it is dated right before she disappeared. 

1937. Katya Komarovsky is studying medicine in Glasgow, living among friends and eager to begin her career as a doctor. But when her spendthrift parents announce that they’ve run out of money and are facing ruin - and that she’ll now have to support them by working as a governess in Vienna - the life she’s dreamed of goes up in smoke. Furiously resentful, Katya rages at her wealthy employer, Thor, for stealing her future - and saddling her with twelve-year-old Gretchen, a deeply troubled child who has only a blazing musical talent to redeem her.

Norway, 1940. Nazis pour into Oslo, a shroud of dread looms over the city, and eighteen-year-old Ingrid Solberg fears the worst. Under German rule, harsh rationing and the exorbitant cost of medicine threaten the lives of many, including Ingrid’s mother. And when Ingrid meets a young SS officer, she’s forced to make a desperate choice. Seventy years later, after the death of Ingrid in her adopted country of Canada, her son, Arnold, finds a disturbing letter in her belongings. He embarks on a journey to Oslo to understand his family’s history....

Paris, 1939: The Nazis think Éliane can't understand German. They’re wrong. They think she’s merely cataloging art in a Louvre museum and unaware they’re stealing national treasures for their private collections. They have no idea she’s carefully decoding their notes and smuggling information to the Resistance. But Éliane is playing a dangerous game. Does she dare trust the man she once loved with her secrets, or will he only betray her once again? 

Each morning Livia Moretti makes her way from an apartment overlooking Florence’s famous Duomo to a nearby café, where she drinks espresso and reads the newspaper. To the crowds of tourists who pass by, nothing about Livia will be memorable. She is simply an old lady. They walk on without knowing the part she played in ensuring the future of this beautiful city. And to Livia now, those dark days feel very far away. But today, when she opens the paper, she sees a name she has not heard for a long time. A name that will bring memories flooding back.

1942. Three years into the war, Pam turns down her hard-won place at Oxford University to become a codebreaker at Bletchley Park. There, she meets two young men both keen to impress her, and Pam finds herself falling hard for one of them. But as the country’s future becomes more uncertain by the day, a tragic turn of events casts doubt on her choice. Present day. Julia is struggling to juggle her career, two children and a husband increasingly jealous of her success. Her brother presents her with the perfect distraction: photos of their grandmother as a young woman at Bletchley Park.

1945: Along with hundreds of other war brides, Betty, Madeline, Alice, and June set sail for New York to be with the men they love. In the days they spend at sea, the four young women become firm friends and vow to stay in touch no matter what their new lives bring. Life in a new country comes with many challenges, but Betty, Madeline, Alice, and June didn't move half way across the world to give up without a fight.

As England prepares to fight the Nazis, three very different women answer the call to mysterious country estate Bletchley Park, where the best minds in Britain train to break German military codes. Vivacious debutante Osla is the girl who has everything - beauty, wealth, and the dashing Prince Philip of Greece sending her roses - but she burns to prove herself as more than a society girl, and puts her fluent German to use as a translator of decoded enemy secrets.  

Germany, 1939: Annaliese is a doctor’s wife, living in an elegant grey stone house with ivy creeping over the balcony. But when her husband is ordered to work at the Dachau labor camp, her ordinary life is turned upside down by the horrors of war. And Annaliese finds herself in grave danger when she dares to fight for love and freedom. America, 1989: Turning the pages of the newspaper, Annaliese gasps when she recognizes the face of a man she thought she’d never see again....

France, 1942. At the end of the day, the schoolteacher releases her pupils. She checks they have their identity passes and warns them not to stop until the German guards have let them through the barrier that separates occupied France from Free France. As the little ones fly across the border and into their mothers' arms, she breathes a sigh of relief. No one is safe now. Not even the children.

Nineteen-year-old Libby moves to Berlin to escape her suffocating family - but instead of offering freedom, the city is under siege by the Nazis. Jewish books are burned, storefronts smashed and every day innocent people vanish into thin air. Libby cannot - will not - turn a blind eye. When Libby meets Harro, she knows there’s more to him than his dazzling smile and cornflower-blue eyes. The whip marks on his back, scars from the SS, tell his true story: He is a resistance fighter.