September 1939. London is in blackout; war has been declared, but Dulcie Treadwell can think only of her heartbreak over American broadcaster, Glenn Reeves, who didn’t say goodbye before leaving for Berlin. Posted to Bletchley Park, Dulcie must concentrate on helping the war effort by cracking the German Enigma codes. The hours are long and the conditions tough, with little recognition from above. Until she breaks her first code. Dulcie finally settles into something she was born to do. But just as she’s proving her worth, a shocking betrayal leads to Dulcie’s brutal dismissal.

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.

Rhoda Middleton suspects her husband Peter is having an affair. But when Rhoda tracks the mysterious woman down, she finds she is not his lover after all, but the wife of his wartime best friend, Archie Foster. There is only one problem - Rhoda has never even heard of Archie Foster.

Pearl has given up on her dreams of being a journalist after being denied a promotion because of her gender. Joining the WAAF as a radio telephone operator for Bomber Command, Pearl's new job at RAF Fenthorpe serves two purposes – providing an income for her grandmother, and keeping a close eye on her younger sister, Thea, an instrument repairer at another Lincolnshire bomber station.

When Katja Heinz secures a job as a typist in Hamburg working for Doctor Viktor’s clinic, she doesn’t expect to be writing up top secret medical records. Doctor Viktor treated soldiers for PTSD at the end of the first world war – and one of the patients was none other than Adolf Hitler.... The notes in his possession declare Hitler unfit for office; exposing such a secret would destroy the Fuhrer's reputation, and perhaps even change the course of the war.

When the Germans march into Denmark, Baron Henrik Ahlefeldt exchanges his nobility for anonymity, assuming a new identity so he can secretly row messages for the Danish Resistance across the waters to Sweden. American physicist Dr. Else Jensen refuses to leave Copenhagen and abandon her research-her life's dream. While printing resistance newspapers, she hears stories of the movement's legendary Havmand-the merman-and wonders if the mysterious and silent shipyard worker living in the same boardinghouse has something to hide. 

Paris, 1944. “Traitor!” yells the crowd as they push me down onto a stool. “Nazi collaborator.” Tears blur my vision as the razor grazes my scalp, waves of blonde hair falling to the ground. As men paint a swastika across my face, I hold onto one small glimmer of hope. They have no idea who I am.

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.

When Stefania Carmichael steps into the mysterious world of Bletchley Park, she immediately finds herself signing the Official Secrets Act. In whispers, she is told that she’s been recruited because of her talent for languages. Before the war ripped Europe apart, Stefania was living in Rome, charming everyone she met, and engaged to the man of her dreams, handsome and brave Matteo. And now everything has changed. With secrets swirling around the building, Stefania finds it hard to know who to trust, until she forms a close bond with two other new recruits.

Paris, 1942. As the Germans occupy the city she calls home, Adele Basset is determined to keep her pupils' spirits up. Their dance class offers a moment of solace in the dark days of occupation. But when the Germans demand the names of her Jewish students, Adele is spurred into action. She can't stand silent while they're taken from her. Hiding her Jewish pupils in the school attic, Adele puts her life on the line in search of an escape.

When three little girls—Anna, Bernie, and Elica—make a pact to be blood sisters for life, they believe nothing can come between them. Anna is from an affluent Jewish family, while Bernie and Elica are from poor Austrian families who barely make ends meet. As they get older, their social differences become all too real. With infectious Jew-hate-laden rhetoric from Nazi Germany spreading into Austria, it is only a matter of time before their bond of friendship gets severely tested.

Liverpool, 1940. Journalist Ruth Holt is struggling in the terror of the Blitz when her young son is suddenly snatched away in broad daylight. Soon after, the kidnappers’ demands arrive. They are working with the Nazis, and she has no choice but to co-operate, or the authorities will learn that she is harbouring secrets of her own. Ruth’s job gives her access to critical information, and if she does not share it with Britain’s enemies, her child will face the consequences. Desperate, she falsifies information, lying to everyone: her employers, her family and her lover.

At the heart of Dover's Market Square lies the Castle's Café. A bustling, homely place run by the formidable Nellie Castle and her six children. Since the scandalous birth of her beloved son 10 years before, Marianne, Nellie's eldest daughter, has preferred to stay in the kitchen, hidden away from the town gossips. Overcome with shame, Marianne has never revealed the name of Donny's father - not even to her own mother. But with World War II just around the corner, Marianne's past catches up with her. And suddenly the lives of the Castle family become a lot more complicated.

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.

Scotland, 1942. The Lumberjills, the newest recruits in the Women’s Timber Corps, arrive in the Scottish Highlands to a hostile reception from doubtful locals. The young women are determined to prove them wrong and serve their country – but they’re also all looking for something more. Can the Lumberjills get through their struggles together – even when tragedy strikes?