Traitor's Gate — Michael Ridpath

Conrad de Lancey is a young Englishman who, disillusioned by his experiences fighting with the International Brigade in Spain against Franco, moves to Berlin - his mother's native country - to become a writer. But it is 1938 and Hitler's Germany isn't the right place for a writer to find peace. Following the death of his cousin Joachim at the hands of the SS, Conrad meets up with Theo von Hertenberg, a university friend from their years together at Oxford, now a German army officer.