That Burning Summer by Lydia Syson

It’s July 1940 on the south coast of England. A plane crash-lands in the marsh, and sixteen-year-old Peggy finds its broken pilot—a young Polish airman named Henryk. Afraid and unwilling to return to the fight, Henryk needs a place to hide, and Peggy helps him find his way to a remote, abandoned church. Meanwhile, Peggy’s eleven-year-old brother Ernest is doing his best to try to understand the war happening around him. He’s reading all the pamphlets—he knows all the rules, he knows exactly what to do in every situation. He’s prepared, but not for Peggy’s hidden pilot.