Shute Nevil. Mysterious Aviator (So Disdained)

Vintage, 2009. First published 1928Peter Moran, a former WWI pilot, manages an English estate. While driving one evening, he encounters a pilot fleeing the forced landing of an airplane. The pilot is Maurice Lenden, with whom Moran served. Lenden tells Moran of his troubled life since the war, doing odd flying jobs and aerial surveys in Honduras. But another country asks Lenden to do covert surveys of England, and he may be guilty of treason.