The Alice Network by Kate Quinn

1947. American college girl Charlie St. Clair is pregnant, unmarried, and on the verge of being thrown out of her family. She’s also nursing a desperate hope that her beloved cousin Rose, who disappeared in Nazi-occupied France during the war, might still be alive. So when Charlie’s parents banish her to Europe, Charlie breaks free and heads to London, determined to find out what happened to Rose. 1915. Eve Gardiner burns to join the fight against the Germans and gets her chance when she’s recruited to work as a spy. Sent into enemy-occupied France, she’s trained by Lili, who manages a vast network of secret agents. 30 years later, haunted by the betrayal that ultimately tore apart the Alice Network, Eve spends her days drunk and secluded in her crumbling London house. Until a young American barges in uttering a name Eve hasn’t heard in decades, and launches them on a mission to find the truth.