Paris 1930s. Childhood companions Fleur and Colette make a vow, under the trailing ivy of their secret garden, that they will be secret sisters forever. But as they grow up, the promises of childhood are put to the ultimate test. For Colette is the daughter of the house, and her life is all jazz clubs, silk dresses and chilled champagne, while Fleur is the orphan niece of the housekeeper and doesn’t feel like she belongs anywhere. Years later, in 1939, life as they know it will never be the same.

When Eleanor Atherton graduates from medical school near the top of her class in 1917, she dreams of going overseas to help the wounded, but her ambition is thwarted at every turn. Eleanor's parents insist she must give up medicine, marry a respectable man, and assume her proper place. While women might serve as ambulance drivers or nurses at the front, they cannot be physicians - that work is too dangerous and frightening. Nevertheless, Eleanor is determined to make more of a contribution than sitting at home knitting for the troops.

1916. At the onset of war, Nurse Pru le Cuirot left her home in Jersey to care for injured soldiers at Ashbury Manor, Dorset. She wanted to do her bit but she never expected to meet Canadian pilot, Jack Garland, so unlike any man she has ever met. When Jack is sent on a dangerous mission and vanishes, Pru is forced to make an agonising decision…one that will haunt them both forever.

At the end of the 1930s, Europe is engulfed in war. Though America is far from the fighting, the streets of New York have become a battlefield. Anti-Semitic and racist groups spread hate. Josef Klein, a German immigrant, remains immune to the troubles roiling his adopted city. Josef’s great passion is the radio. His skill and technical abilities attract the attention of influential men who offer him a job as a shortwave operator. But when Josef begins to understand what they’re doing, it’s too late....

Hiding the worn piece of paper among her father’s watch deliveries, her eyes fill with tears at the memory of her brave friend walking towards the Nazi soldiers, and the sharp sound of gun fire. Her friend sacrificed herself so that she could deliver this message. But if she hands it over, the love of her life will die...1942, Geneva: As her radio crackles with heart-breaking news from occupied France, Valérie Hallez gazes towards the snow-covered Alps after a long day helping her father, a local watchmaker.

It was in 1943. On the Black Sea, the Russians were fighting a desperate battle to regain control. But the Russians’ one real weakness was on the water: whatever they did, the Germans did it better, and the daring hit-and-run tactics of the E-boats plagued them. At last the British agreed to send them a small flotilla of motor torpedo boats under the command of John Devane. Devane had been in the Navy since the outbreak of war.

New Orleans, 1944. Sabotage—that's the word on factory worker Justine Byrne's mind as she is repeatedly called to weld machine parts that keep failing with no clear cause. Could someone inside the secretive Carbon Division be deliberately undermining the factory's war efforts? Raised by her late parents to think logically, she also can't help wondering just what the oddly shaped carbon gadgets she assembles day after day have to do with the boats the factory builds....

World War II London: When Victoire “Paddy” Bennett first walks into the Admiralty’s Room 39, home to the Intelligence Division, all the bright and lively young woman expects is a secretarial position to the charismatic Commander Ian Fleming. But soon her job is so much more, and when Fleming proposes a daring plot to deceive the Germans about Allied invasion plans he requests the newlywed Paddy's help. She jumps at the chance to work as an agent in the field, even after the operation begins to affect her marriage. But could doing her duty for King and country come at too great a cost?

Three very different girls sign up as trainee nurses at a big London teaching hospital in 1934. Dora leaves her overcrowded, squalid working-class home for a better life. But has she got what it takes to keep up with other, better-educated girls? And will her hated stepfather ever let her go? Helen is born for the job; her brother is a doctor, her all-powerful mother a hospital trustee. But will Helen’s secret misery be her downfall? An aristocratic rebel, Millie’s carefree attitude will find her up in front of Matron again and again. Will she ever care enough to make a nurse? Or will she go back to the glamorous life she was born to?

Artist Marguerite Segal is recruited by British Intelligence into befriending Etienne Valade, a local priest. Her mission is to persuade him to pass on information from the high-ranking German officers who attend his church: evidence of their war crimes. Connected by a passion for art, Marguerite and Etienne soon fall in love, but their association increasingly puts her at danger of violent reprisals. With his church frequented by Nazis, Etienne is a suspected collaborator, and distrust is high.

Born to a French mother and an English father, Charlotte Bray has always felt like an outsider in her Cornish fishing village. She spends her days on her father's fishing boat, helping to feed a nation at war. But the war brings devastation, and her world is forever changed by tragedy. With nothing left to lose, she accepts a mysterious invitation to work for the War Office as a spy. She soon finds herself in Nazi-occupied Paris with a new identity. Charlotte begins working under the sombre but handsome Frenchman Pierre Lesieur. But do his allegiances lie elsewhere?

The year 1963: Reeling from the death of her mother and President Kennedy’s assassination, Catherine Gray shows up on Elizabeth Bentley’s doorstep demanding answers to the shocking mystery she just uncovered about her family. What she doesn’t expect is for Bentley to ensnare her in her own story of becoming a controversial World War II spy and Cold War informer.

London 1940. As the war rages in Europe, Rose Brown steps on board a ship bound for America, hoping to escape the danger. She's frightened, but her widowed mammy and three sisters in Ireland need the money she earns as nanny to the rich Townsend family. But while Rose plays with baby Sarah in the salty spray on deck, disaster strikes, and the ocean liner begins to sink. In the chaos, Rose and the baby are separated from the family.

July, 1940. Blitz-ridden London: Marnie Fern’s life is torn apart when her grandfather is killed in an air raid. But once she discovers that he’d been working undercover as a radio operative – or pianist – for the Dutch resistance, Marnie knows she must complete his mission – no matter the cost. Nazi-occupied Amsterdam: At the other end of the wireless, fellow pianist Corrie Bakker is caught in a dangerous game of cat-and-mouse as she desperately tries to keep her loved ones out of the line of fire – even if it means sacrificing herself.

The occupation has taken much from the Cotillard sisters, and as the Germans increase their forces in the seaside town of Boulogne-sur-Mer, Gabriella, Martine and Simone can’t escape the feeling that the walls are closing in. Yet, just as they should be trying to stay under the radar, Martine’s discovery of a British messenger pigeon leads them down a new and dangerous path.