The Nightingale by Kristin Hannah
WWII is on, the Nazis have invaded, and France is occupied. Elder sister Vianne is committed to surviving and to keeping her daughter safe. Younger sister Isabelle is outraged, and determined to join the Résistance and beat the Germans. The siblings rarely agree and are separated by time and politics for almost the entire duration of the conflict.
The point is made several times during the story that "war stories" are almost always about (and told by) men, and that the Nazis often overlooked the role of women in warfare, sometimes to the tremendous detriment of the Third Reich.
Not everything goes well, of course. Some of the wrong people are taken away, some of the characters that readers attach to come to grievous harm. Very few of the characters would be objectively considered "good people"...and yet, the details of their lives are so compelling that the book is difficult to put down.
Written for adult audiences but with plenty of teen appeal, especially for readers of Code Name Verity and Rose Under Fire. Sexual situations are mostly off-page, but some of the violence (and torture) is not.
Highly recommended for readers ages 14 to adult, and especially for book discussion groups.