Code Name Verity by Elizabeth Wein (2012)

Fascinating young adult novel about a young woman working as a secret agent who is captured by the Gestapo in Nazi-occupied France, and her friend, a pilot working with the civilian air force.

Divided into two parts, the first unfolds as a written confession, but all is not as it seems. The second follows the pilot after crash landing in France. Gripping, suspenseful, and chilling, this is a great story of friendship, but also of parts of World War II that we don't necessarily always hear about.