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, Steffie was living in Rome, charming everyone she met with her quick wit and sharp mind, and engaged to the man of her dreams, handsome and brave Matteo. Now everything has changed. With secrets swirling around the building, Steffie finds it hard to know who to trust, until she forms a close bond with two other new recruits. Ailsa is a gifted radio operator and Fran a logistics genius, and the two women help Steffie navigate her new world of code-breaking. But even though Steffie's skills are crucial to the war effort, her position is put in jeopardy when Italy joins the opposite side of the battle and her beloved fiancé becomes the enemy. Her heart belongs to Matteo, but Steffie knows she must do whatever it takes to help England win the war. So when she is asked to go on a classified mission, she jumps at the chance. But it soon becomes clear there's a traitor in their midst, and all eyes turn to her.