The Rose Code by Kate Quinn

"The Rose Code" is a historical fiction novel by Kate Quinn, set during World War II at Bletchley Park, a British codebreaking center. The story follows three young women, Osla, Mab, and Beth, who become close friends while working as codebreakers. The narrative shifts between their wartime experiences and their lives in 1947, where they must reunite to solve a mystery and uncover a traitor