The Alice Network by Kate Quinn

In May 1947, Charlotte "Charlie" St. Clair and her mother have crossed the Atlantic so the unwed Charlie can discreetly end her pregnancy in a Swiss clinic. A chance to search for her beloved cousin Rose, who disappeared during World War II, gives Charlie the courage to break free and head to London. Rose may have been involved in the French Resistance, and her last known connection was a woman named Eve, who carries her own war secrets. Read a sample.