The Alice Network by Kate Quinn

This historical novel tells the story of two girls, during two World Wars, and how their lives become intertwined. Evelyn Gardiner was a WWI spy in her youth, and has aged and become cranky by the time of the second World War. She is frankly annoyed when Charlie St. Clair, a college-aged American, arrives at her doorstep looking for her long-lost cousin. Charlie hadn’t heard from her cousin, Rose since the end of WWII and the two embark on a quest to find Rose, as well as the truths of Evelyn’s past. With abundant twists and turns, The Alice Network is equally riveting and heartwarming.