The Secrets We Left Behind by Soraya M. Lane

How far will they go for family, friendship, and love?

Occupied France, 1940. When the staff at a field hospital draw straws to find out who will join the evacuation from Dunkirk, Nurse Cate is left behind. But when the Nazis arrive to claim prisoners of war, she takes her chance and flees into the night, taking one patient with her.
Fifty miles away, the surrendering soldiers of the Royal Norfolk Regiment are shot dead by the advancing Germans. Beneath the pile of bodies two men survive, crawling to the safety of a nearby farmhouse, where sisters Elise and Adelaide risk their lives to take them in. When Cate, too, arrives at their door with her injured soldier, the pressure mounts.
The sisters are risking everything to keep their visitors safe. But with the Nazis coming ever closer and relationships in the farmhouse intensifying, they must all question the sacrifices they are willing to make for the lives of others. How far will they go for family, friendship, and love?