Valentine’s Day celebrates romance, but it’s easy to forget that “romance” can refer to more than courtship and sweet nothings. Up until the 20th century, and sometimes still, fiction was regularly divided into two categories: Novels were realistic accounts of contemporary life and manner, often focusing on love and marriage, while romances were adventure stories, characterized by heroic exploits, derring-do and, usually, a certain amount of fantasy. “Pride and Prejudice” and “Madame Bovary” are novels; “King Solomon’s Mines” and “The Time Machine” are romances.

“The Prisoner of Zenda,” by Anthony Hope (Penguin )

However, such genre divisions have always been extremely porous, and one of the world’s greatest romances — Anthony Hope’s “The Prisoner of Zenda” (1894) — is also the story of a great romance. It makes for perfect reading in the afterglow of Valentine’s Day.

The book opens like an Oscar Wilde comedy, with Rudolf Rassendyll being verbally assailed at the breakfast table by his brother’s wife. When, asks the pert Lady Bursledon, is he going to make something of himself? In the course of their repartee, we learn that the cheerful, easygoing Rudolf has red hair, the visible reminder of a great-grandmother’s indiscretion with a member of the royal house of Ruritania.

Ruritania! Located somewhere near Germany and Bohemia, connected by railroad with Dresden, Ruritania is — on the surface — the sort of country you might associate with a Viennese operetta. The capital is Strelsau; there’s a formidable castle called Zenda, affairs of honor are settled with duels, and everything feels faintly medieval. Gentleman carry swords as well as pistols.

On a whim, Rudolf — who narrates the story — decides to visit this land of his distaff ancestor, intending to watch the coronation of its new king. At an inn, though, he learns that many people view the future sovereign as just a boar-hunting, heavy-drinking good ol’ boy. Little wonder that Princess Flavia doesn’t much care for him, though everyone expects that she is her royal cousin’s destined bride. In fact, quite a few people would much rather see his half brother, Duke Michael, on the throne. Those people include the ruthless Michael himself.

Hope conveys all this background information in just his first two chapters. Unlike many 19th-century novels, “The Prisoner of Zenda” zips right along, the reader’s attention never flags, and the prose is quietly attractive: “Look where I would, I saw nothing that made life sweet to me, and I took my life in my hand and carried it carelessly as a man dangles an old glove.”

The day before the coronation, Rudolf goes for a walk in the woods, takes a bucolic nap and is awakened by three amazed gentlemen, Colonel Sapt, Fritz von Tarlenheim and the future King Rudolf the Fifth, who — you guessed it — looks almost exactly like Rudolf Rassendyll. Blood and red hair will tell. The four spend a merry evening in the royal hunting lodge.

That night Duke Michael drugs his hated brother so that he will be unable to attend his own coronation. Yet if the king fails to be crowned at the appointed time, Ruritania might suffer a coup d’état. But wait! What if? — no, it would never work, but, then again, maybe it would. Could Mr. Rassendyll take the place of the king, if only for the ceremony? After a moment’s hesitation, our hero agrees to play this risky, larky game.

However, that game soon grows more complicated, and troubling, when the Englishman and Princess Flavia finally meet. The princess suddenly finds that her royal cousin now seems indefinably more manly, possibly even lovable. Rudolf, for his part, is immediately smitten — and hopelessly so, for the next day he must trade places with Ruritania’s rightful ruler and the beautiful Flavia will then be just a sweet memory. Ha!

Before the switch can be made, Duke Michael spirits the king away to Zenda castle, making him a hostage and pawn in a deadly political chess game. As it is, only a handful of people know about the substitution scheme, and that number doesn’t include Princess Flavia. In the end, Rudolf undertakes a perilous, one-man guerrilla operation to rescue the true king. Love, politics, honor, duty — all contend violently in the hearts of the book’s major characters, as Hope leads the reader from one excitement to the next, before a well-prepared surprise finale. Adventure and romance don’t come any better.

“The Prisoner of Zenda: Rupert of Hentzau” (Penguin Classics)

Plus, there’s a pretty good sequel. In “The Prisoner of Zenda,” Rudolf Rassendyll looks physically like the king but in personality he resembles his own dark-side double, the dashing Rupert of Hentzau. A member of the Six, as Duke Michael’s henchmen are called, Rupert is impulsive, untrustworthy, murderous, a Don Juan who doesn’t take no for an answer and utterly charismatic. At one point, trying to escape imminent capture, he commandeers a horse being ridden by a peasant’s little girl. He “lifted her down amid her shrieks — the sight of him frightened her; but he treated her gently, laughed, kissed her, and gave her money.” Rupert then pauses to banter with Rudolf before galloping off: “And I watched him go down the long avenue, riding as though he rode for his pleasure and singing as he went. . . . Thus he vanished — reckless and wary, graceful and graceless, handsome, debonair, vile and unconquered.”

Significantly, Rupert bids Rudolf “Au revoir.” True to those words, the two adversaries face off again when the daring scoundrel returns to seek vengeance in “Rupert of Hentzau” (1898). An injudicious letter, races against time, renewed impostures, fights to the finish, a single red rose and the words “Rudolf — Flavia — always.” What more could you want for a Valentine’s Day weekend? Yet, good as it is, the later, darker-toned sequel can’t match the exuberant springtime brio of “The Prisoner of Zenda” itself, the nonpareil masterpiece of romance.

Michael Dirda reviews books each Thursday for The Washington Post.

The Prisoner of Zenda

By Anthony Hope

Penguin. 199 pp. $15