The decline of the pure detective story in recent years was probably inevitable. After all, there are only so many motives for killing someone, and contemporary society virtually removed one of the most popular (killing a spouse because of another love interest seems utterly Victorian now that divorce is so easy to obtain). Even schoolchildren know police should “follow the money” for the other most common motive.

Furthermore, few authors have the ability to contrive complex mysteries, with apparently airtight alibis being broken down, clues placed so cleverly before the reader’s eyes that they fail to see them or understand their significance, and motives so powerful yet believable that the killers are not merely a necessary piece of the puzzle but part of a cohesive and satisfying story.

As heroes and heroines of today’s traditional mysteries have come to rely more and more on coincidence, luck, a hunch, or a brilliant housepet to solve crimes, readers have also become less demanding of contemporary writers. They’re willing to settle for a less-than-perfect plot just so long as they like the lead character.

Readers also have become impatient. Bombarded daily with quick cuts of movies, television programs, and commercials, they are unwilling to work through discussions of railroad timetables, tides, or how long it takes for a sprig of parsley to sink into a bar of butter on a summer day. They seek movement and action – hence the increased popularity of the thriller.

The thriller genre, like all the categories of mystery fiction I have discussed during the past few weeks, is as difficult to define as art or pornography. It takes in tales of espionage, political nastiness, financial schemes, adventure, some military fiction, high-tech shenanigans, and even weird religious plots. But its borders are as fuzzy as my memory after a second bottle of wine.

STRUCTURE A single hero (or, in very recent years with increasing frequency, heroine), a partnership, or a small group of experts battle a foreign power, criminal organization, or ruthless super-genius intent on seizing control of (a) America), (b) the world, or (c) a phenomenal amount of money. The action involves very fast vehicles, serious weaponry, lots of explosions, a huge body count, and the most beautiful 30-year-old woman in the world. She is always the world’s leading expert on something or other, and she is always single.

HOW TO TELL YOU’RE HOLDING ONE These books are frequently thick, and the dust jackets (or covers, as many thrillers are paperback originals) often feature an American flag, a swastika or a hammer and sickle, an explosion, and a weapon, as well as an illustration of the aforementioned woman in very tight garments running toward or away from someone or something. Frequently she will be holding the hand of a very handsome and muscular guy. Large pieces of modern machinery are often in evidence, as is the figure of a monomaniacal fiend of some stripe. Such lines as “the fate of the world” and “only X can prevent” may appear, as might “heart-pounding,” “fast-paced,” and “explosive action.”

THE BEGINNING Spies have always been with us (note Judas Iscariot). So have figures intent on world domination (Alexander the Great, Genghis Khan). But the literary thriller did not begin until 1821. That’s when James Fenimore Cooper wrote “The Spy,” the story of a heroic American agent during the Revolutionary War. Distinguished authors as well as hacks (almost always British), went on to write spy thrillers, notably Erskine Childers with “The Riddle of the Sands” (1903), Joseph Conrad with “The Secret Agent” (1907), Sax Rohmer (whose Dr. Fu Manchu series began in 1913 and continued into the 1950s), W. Somerset Maugham (whose “Ashenden” is frequently cited as the origin of the modern espionage novel), and E. Phillips Oppenheim (the author of more than a hundred books, most of which are thrillers).

THE GREATS John Buchan (his Richard Hannay novels, especially “The 39 Steps”), Eric Ambler (“A Coffin for Dimitrios,” “Epitaph for a Spy”), Graham Greene (“The Third Man,” “This Gun for Hire,” “Orient Express,” “Confidential Agent”), Ian Fleming (and his utterly unrealistic but nonetheless captivating hero, James Bond). John Gardner actually wrote more Bond novels than Fleming, but his best works are about Big Herbie Kruger, including one of the half-dozen greatest spy novels ever written, “The Garden of Weapons.” Also don’t miss Len Deighton, Alastair MacLean, and Adam Hall, creator of Quiller.

All these men are British. Among Americans, Ross Thomas wrote every type of thriller imaginable, no two alike. Also try Robert Ludlum, Francis Van Wyck Mason and his Colonel North series, Richard Condon (“The Manchurian Candidate”), Thomas Gifford (“The Wind-Chill Factor), and Brian Garfield (“Hopscotch”).

TODAY’S BEST The great Charles McCarry is the most poetic of all American spy writers, especially in “The Tears of Autumn,” “The Secret Lovers,” and “The Last Supper.” Alan Furst, with his World War II thrillers, has taken the mantle of Ambler and wrapped himself in it. Robert Littell’s first book, “The Defection of A.J. Lewinter,” was as terrific as his most recent, “Legends.” And Nelson DeMille manages the rare feat of writing beautifully and being a bestseller.

All of these men are Americans. Among the best of the British, John le Carre has no peer as a prose stylist, most famously in the Karla novels, “Tinker, Tailor, Soldier, Spy,” “The Honorable Schoolboy,” and “Smiley’s People,” as well as the iconic “The Spy Who Came in From the Cold.” Frederic Forsyth’s “The Day of the Jackal” is white-knuckle suspense, best-selling Ken Follett’s “Eye of the Needle” began a monstrously successful career, and Brian Freemantle’s Charlie Muffin series brings the rare element of humor into the thriller.

Next week: Hardboiled Fiction

Mr. Penzler is the proprietor of the Mysterious Bookshop in Manhattan and the series editor of the annual “Best American Mystery Stories.” He can be reached at openzler@nysun.com.