A classic swashbuckling novel by Anthony Hope, first published in 1894, and English literature's answer to Alexandre Dumas classics such as The Count of Monte Cristo. The story of mistaken identity was successfully translated to the silver screen twice, and its fictional setting of Ruritania has become a byword for royal ceremony laced with intrigue.

Zenda's MacGuffin is the striking resemblance between the stiff upper lipped hero, Rudolf Rassendyll, and the ruling Elphberg dynasty of Ruritania, the result of King Rudolf III's adventures on the wrong side of the blankets during a state visit to England in 1733. The Elphberg blood makes itself known every so often in a characteristically shaped nose and red hair, which, for all we know, will eventually be added to the gossip about Prince Harry.

With the disregard of any self-respecting English hero for perfectly sensible warnings, Rassendyll takes it upon himself to visit Ruritania to watch the coronation of King Rudolf V. Innocent Victorian that he is, he accepts the invitation of two strange men he meets in the woods to dine with his lookalike, the King.

Lo and behold, their wine has been drugged by the King's wicked stepbrother Black Michael and Rudolf V is insensible for the morning of his coronation. (In a thousand years of fast-living kings, it can't have been the first time.) Roped in by the King's loyal servants to understudy Rudolf V during the ceremony in the Ruritanian capital Strelsau, Rassendyll makes the acquaintance of Princess Flavia, the future Queen Consort. It's an ill wind that blows nobody any good.

Confounded by the quick thinking of Colonel Sapt and his aide Fritz von Tarlenheim, and their sheer blind luck in stumbling across a dead ringer for the King, Black Michael meanwhile abstracts the rightful King to his castle of Zenda. Rassendyll is provided with the opportunity to test his fencing skills against the Duke of Strelsau's six dastardly henchmen, and Hope with the rationale for the remaining eighteen chapters.

As the plot evolves, or rather, twists and turns around a moat, a ladder, and an impregnable cell, Hope appears less attached to Black Michael than to his lead henchman Rupert of Hentzau, Rassendyll's nemesis and an all-round bad egg. In his way, Hentzau is as dashing as his adversary, with all the arrogance and flair to be expected of a series villain; he's duly accorded a mysterious exit to match.

After a regulation tearful but dutiful farewell to Flavia, Rassendyll returns to London ready to be called upon in three years' time for The Prisoner of Zenda's lesser-known sequel, titled - perhaps an admission of Hope's real sympathies - Rupert of Hentzau. Published in 1898, this time in the serial form that served Dumas so well, Rupert is a bleaker work, with an elegiac finale deserving the full screen funeral treatment and ensuring Hope would never be called upon for a trilogy.

Hope had previously returned to Ruritania in 1896 with a collection of short stories entitled The Heart of Princess Osra, set during the reign of Rudolf III. Later in life, he tried to repeat the Ruritanian formula with Sophy of Kravonia, but evidently ran up against the law of diminishing returns.

Six films have been made of The Prisoner of Zenda, but the most famous are the 1937 and 1952 versions. The first, assembling a run-down of action stars of the era, features Ronald Colman as both Rudolfs, Douglas Fairbanks Jr. as Hentzau, and David Niven as von Tarlenheim, as well as Mary Astor in the role of Antoinette de Mauban, Black Michael's scheming love-interest and a not entirely successful echo of Milady de Winter of The Three Musketeers.

1957 paired matinee idol Stewart Granger, fresh from his swordsmanship in Scaramouche, as the two Rudolfs with the Scottish actress Deborah Kerr, repeating their partnership in King Solomon's Mines.

Zenda's legacy to the language has been the invention of Ruritania, commonly supposed, without any indication in the book, to be a Balkan monarchy. In fact, Ruritania's prevalence of German names suggests that - if you want to peep behind the curtain at all - it was probably intended as another Liechtenstein overlooked in the process of German unification.

Zenda castle, too, seems to have its analogue in the real world, although one of which there is no reason for Hope to have been aware. Black Michael's stronghold is a medieval fortress with a modern chateau attached; Trsat Castle, overlooking the Croatian city of Rijeka, was fortified in the sixteenth century against the corsairs of the Ottoman Empire and renovated, by the Austro-Irish general who acquired it 300 years later, with a neo-classical folly occupying most of its grounds.