The Great Impersonation — E. Phillips Oppenheim / Edward Phillips Oppenheim

The year is 1913. The disgraced and formerly penniless aristocrat Sir Everard Dominey returns from German East Africa a reformed and wealthy man determined to take his place in English society. But is he Sir Everard or the German spy, Baron Leopold von Ragastein? Leopold, educated at Eton and Oxford with the Englishman, bears a striking resemblance to Dominey and was often taken as his double at school. After a chance encounter in Africa, one of them has returned. But who?

Originally published in 1913, 'The Great Impersonation' is probably the most famous spy novel of all time. Besides the Kaiser and a whole host of Dukes, Duchesses, Ambassadors, German agents and silly young Englishman, there's the Princess Eiderstrom, "one of the most passionate women in Europe," who is desperately in love with Leopold; Sir Everard's insane wife, Lady Dominey, who has vowed to kill him if he should every return home; the frightening Mrs. Unthank, Lady Dominey's only companion, and her son, Roger Unthank, whom every one believes Sir Everard murdered, and whose spirit is popularly supposed to haunt the ancestral home.