On a "raw and damp" morning in the England of 1733, according to the author's premise, a British nobleman named James Rassendyll fought a duel with a visiting prince of the House of Elphberg, the royal family of the (fictional) Central European country of Ruritania. Severely wounded, the prince returned home, where he recovered and subsequently ascended the throne, married and continued the royal line. James contracted a severe respiratory illness on the occasion and died of it (this was the pre-antibiotic era) six months later, leaving his beautiful widow seven months pregnant with her first son. When born, the boy was legally presumed to be her husband's child and succeeded to the earldom. BUT, he proved to have the distinctive Elphberg long, sharp, straight nose, dark red hair and blue eyes, features not typical of the previous Rassendylls. Even in an age before DNA testing and real knowledge of genetics, this provoked conjecture. (Of course, in the 18th century, despite both lip service to Christian morals and a traditional sexual double standard, the English aristocracy tended to politely overlook rampant marital infidelity by both husbands and wives, as long as neither spouse was tactless enough to mention it in public.)
Elphberg features continued to crop out in the subsequent generations of Rassendylls, who privately knew (though they didn't broadcast the fact) that they were essentially an out-of-wedlock branch of the Elphbergs. In the author's present, the Elphberg look is particularly marked in younger son Rudolf. He's a former Army officer, now unemployed and (having the late Victorian equivalent of a trust fund) not at all interested in being employed. His military training has made him very competent with a sword and a pistol, and a good rider; he also happened to be educated in a German university, so is German-speaking. (Although the rupture of World War I tended to subsequently obscure this, in real life England and Germany had a lot of that kind of cultural contact in the pre-war generations, and even a fair amount of intermarriage in the aristocratic families; so Rudolf's college experience isn't at all unrealistic.) The Ruritanian king having died recently, Rudolf decides on a whim to attend the coronation of the new king, his namesake Prince Rudolf. When the two meet, they discover that they're physically almost exact doubles. That resemblance is going to come in very handy, because trouble is brewing in Ruritania. King Rudolf's not-exactly-loving younger half-brother Duke Michael would prefer to be king himself; and neither filial affection nor respect for human life are very high on his list of values.
Rudolf Rassendyll is a first-person narrator, and it took me a while to warm up to him. He came across to me initially as too flippant, and exuding a smug attitude of entitlement that I consider one of the worst consequences of hereditary aristocracy. But his tone gets more serious before long; and this proved to be at once a very stirring tale of intrigue, violence, plotting and counter-plotting, with a lot of suspense and action in the face of very real challenges and jeopardies, and a serious exploration of challenging questions of right and wrong, the meaning and value of honor and integrity, of choices between self-service and self-sacrifice. The (clean) romantic component of the story is flawed by an "insta-love" factor which, on examination, isn't too credible; but it still lends a very real, compelling emotional power to the tale. Hope doesn't examine the political and socio-economic realities of the class-conscious, largely elitist and exploitative social order in which his characters move (an order destined to be swept away in about 20 years in the convulsions of the Great War), and that's a detrimental blind spot. But he also evokes a mind-set of principle, honor and integrity which the war would also largely sweep away --and which is much more missed by those who have the discernment to miss such things.
One final comment needs to be made. Another Goodreader, commenting on the book, complained of the lack of female characters, save for the "simpering princess" and a housekeeper whose role is minor. However, Princess Flavia never simpers here; she comes across as a strong-inside, intelligent and morally sensitive woman of patriotism and principle, who inspires real respect. And she's far from the only significant female character here: Antoinette de Mauban, Lady Burlesdon, and even the innkeeper's daughter all play important roles in the story, in their different ways, and they're all well-drawn, and even sympathetic characters (despite foibles), who come across as capable people, not caricatures of female ineptitude. Granted, in keeping with 19th-century gender attitudes, they aren't primarily fighters (though one might give some characters, and readers, a surprise in that regard). But this is far from being the kind of "guys only, no girls allowed!" book that some of the novels by Hope's contemporary, Robert Louis Stevenson, are.
Overall, this was a book I liked more than I expected to. I'd recommend it to all fans of Romantic classics, and especially of action-adventure fiction.