When a sudden reassignment gives Lily Baker only three days to report to mysterious Bletchley Park, she’s confused but excitedly answers duty’s call. Learning the reputed madhouse is actually the clandestine home of Allied codebreakers, Lily walks a fine line between guarding British secrets and protecting her heart. But when she overhears that a spy could be hidden among the eclectic mix of codebreakers, she is determined to uncover which of her new friends is the traitor.

When duty calls, East End girl Minnie Wolton isn’t afraid to do her bit. She’s excited to be joining the ATS girls and although she knows life at the barracks will be tough, she’s not one to quit! She just hopes the other girls are all good sorts. With her husband away fighting, Eileen Ruffel is glad of the break from her unhappy marriage. She just wants to make a success of the ATS girls and maybe find happiness too. Along with the other girls, Minnie and Eileen strike up a firm friendship. The training is hard, but they are determined to prove they are the best new recruits.

1940, London. When Cordelia accepts the post of head librarian in Silver Town Library, her mother is more than a little disapproving. The East End has high levels of poverty and illiteracy, and her mother says it’s no place for a woman of her status. But Cordelia is determined to make a difference in these times of strife, and along with her colleagues, Jane and Mavis, she begins to help the local community, making sure everyone knows what the library can offer them. And maybe even a romance will blossom.

Lily Baker wants more from life. Working at the local cinema, she saves her pennies so she can have a chance to get ahead. After she’s attacked one night while locking up the cinema, she loses her heart to her dashing rescuer…But this lovely man is as different from her as can be. When the town is divided, pitting the wealthy elite against the poor working class folk like Lily, she finds her allegiance is torn.

As war rages, Barbara Sinclair is desperate to escape her unhappy home life. And with the threat of German bombs ever present, Barbara reluctantly agrees to marry John, her childhood friend, who is leaving to join the RAF. But an encounter with Alex Everton, a dashing Spitfire pilot, complicates matters for Barbara. With emotions running high, she begins to question whether she has made a terrible mistake. With the constant threat of death all around her, Barbara must try to find a way to deal with the complexities of her difficult home life and her emotional relationships, too.

After Pearl's home is destroyed in the Exeter Blitz, so too are her dreams of performing onstage. Finding work as a bus conductress instead, a chance encounter revives her hopes once more, and soon she is singing for the troops alongside new friend Ivy. When agent Gordon Gold approaches them, Ivy jumps to sign with him and sets off for the bright lights of London. But Pearl is wary of the charming man and decides to stay, watching her friend go with a heavy heart. A year later, while Pearl is struck mute by an illness, Ivy returns - and is quick to seize the chance to fill Pearl's place.

Victoria Bahani, the privileged seventeen-year-old, daughter of the Rajah of Marpur and an English woman, has always believed she would marry an Englishman. And when she meets Captain Henry Hindley-Jones she knows he’s exactly the kind of man she’s been thinking of. But when war breaks out everything changes for Victoria. With Henry away fighting, Victoria must try and find her own path in life and also do her duty for her king and country. Signing up to be a nurse in the Queen Alexandra’s Nursing Corp, Victoria must leave behind the country she loves for a life of danger and duty.

When Sophie Weiss boards the SS St Louis, she has no reason to stay in Germany. The Nazis have taken everything from her, and her only hope is escape. But when she meets fellow Jewish refugees Rosa, Hannah and Rachel on board, the friendship they form gives Sophie hope that there can be happiness in her future, after all.

Kitty Wilson, who, after losing her father, rejects the unsuitable suitor her mother has chosen. Abandoned by her mother, Kitty faces the challenges of navigating life alone. Amidst the turmoil, Kitty finds solace and support from friends, securing a promotion at Harpers Emporium. However, tragedy looms, threatening to shatter her newfound stability. Sally and Ben Harper face their own challenges. A decision by Ben regarding the restaurant, made without consulting his partner Jack Burrows, jeopardizes not only their friendship but also the stability of Harpers itself.

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.

1941. The Blitz rages over London. And even in Cornwall, the war is being fought. When Violet loses her sister in the Blitz, she must take her nieces to safety in Cornwall. On the coast, she meets carefree chorus girl Eva, who is also running from the dangers of London. But Porthcurno hides a secret military base, and soon Violet and Eva realise there’s a battle to fight in Cornwall, too. Together with local Hazel, who works on the base, they must come together to help the war effort. But will their friendship be enough to keep them safe? 

Matriarch Kitty Conlon is missing her son Patrick, proud but fearful of the fate of his Spitfire, while spinster Mavis welcomes a new lodger, WAAF Anna Carswell who is delighted by the Weaver Street welcome after a loveless childhood. At number nine, Maggie Stubbs worries nightly as her daughter Lily patrols the streets to protect the neighbours during air raids in her role as ARP Warden, and when an unexploded bomb is discovered at the allotment, danger comes terrifyingly close to Weaver Street.

October 1940. When VAD nurse Evie narrowly escapes being killed in an air raid during the London Blitz, it propels her to make a life-changing decision to break free of her troubled and unhappy life. She escapes to the Norfolk countryside to start afresh, with a job at the newly opened Great Plumstead Hall hospital, and a wonderful new home at Rookery House. The community of Great Plumstead welcomes evacuees to the village—mothers and children bombed out of their London homes. Sisters Prue and Thea, along with members of The Mother's Day Club, help the new arrivals settle in.

Essex 1941. Unhappy with life at home with her privileged family, Hannah Austen-Bagshaw runs away to join the Land Girls Army, carrying with her a dark and terrible secret. Life on the farm is tough, but when Hannah meets handsome working-class flight lieutenant Jack, they form an immediate friendship. But unbeknownst to Jack, Hannah is sheltering a young German pilot who has crash landed in a nearby field. Torn between her duty and her humanity, Hannah knows she risks being arrested as a traitor, but she cannot see the young pilot suffer.

England, 1943: Deciding to throw herself into war work, Nancy Callaghan joins the Special Operations Executive in Baker Street. There, she begins solving ‘indecipherables’ – scrambled messages from agents in the field. Then Nancy meets Tom Lockwood, a quiet genius when it comes to coding. Together they come up with the idea of printing codes on silk, so agents can hide them in their clothing to avoid detection by the enemy. Nancy and Tom grow close, and soon she is hopelessly in love. But there is a traitor in Baker Street, and suspicions turn towards Tom.