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.

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.

London, 1962: The world is teetering on the brink of nuclear war but life must go on. Celia Duchesne longs for a career, but with no means or qualifications, passes her time working at a dusty bookshop. The day a handsome American enters the shop, she thinks she might have found her way out of the monotony. Just as the excitement of a budding relationship engulfs her, a devastating secret draws her into the murky world of espionage.

It is 1939, and working-class Evie Bishop has received a scholarship to study mathematics at Oxford when tragedy turns her life upside down. Evie must seek a new future for herself and, inspired to contribute to the war effort, joins the Women’s Auxiliary Air Force as an Ops Room plotter. Posted to a fighter station on the Sussex Coast, Evie befriends two other WAAFs. But the German bombers seem to know more than they should about the base’s operations, and soon Evie, May and Jess are caught up in a world more dangerous than they ever imagined.

London, 1938: The bookstore just doesn’t feel the same to Gertie Bingham ever since the death of her beloved husband Harry. Bingham Books was a dream they shared together, and without Harry, Gertie wonders if it’s time to take her faithful old lab, Hemingway, and retire to the seaside. But fate has other plans for Gertie. In Germany, Hitler is on the rise, and Jewish families are making the heart-wrenching decision to send their children away from the growing turmoil. After a nudge from her dear friend Charles, Gertie decides to take in one of these refugees.