The earliest mystery stories were, if you’ll pardon the expression, deadly serious. The logic was, evidently, that murder is no laughing matter. You would have to look very hard indeed to find much jocularity in the crime fiction of Poe, Dickens, Collins, Gaboriau, and Doyle.

After the turn of the 19th century, there was occasional lightness of tone in the works of G.K. Chesterton, A.A. Milne, and Mary Roberts Rinehart. Humorists such as Mark Twain, John Kendrick Bangs, Stephen Leacock, P.G. Wodehouse, and Damon Runyon set their hand at writing parodies of mystery stories.

In the Golden Age of mystery fiction (between the two world wars), the adventures of thieves and con men were frequently presented as if their crimes were really all in good fun. In later years, it was increasingly common for elements of humor to creep into books and stories, notably in hard-boiled fiction, as wisecracks rained down on cops, suspects, and everyone else within earshot.

Today it is almost more common than not to find humor in a detective story, or at least attempted humor. But no literary genre is more difficult to write than humor, because it is so difficult to find that common observation, insight, or wordplay universally regarded as funny.

Silly is easy, just as buffoonery in cinema or on the stage is easy, but funny – the kind of moment that catches you by surprise and makes you laugh out loud – is hard. You know how to tell when something is genuinely funny? When you laugh instead of saying, “That’s funny.”

Combining a mystery novel, which is pretty difficult to write in the first place, with humor is a real challenge – one that, alas, too many paperback-original writers flunk. But this summer there is an excellent little group of humorous mysteries available, and you can have a fine old time with them.

Inevitably, if one mentions humor in the mystery world, Donald E. Westlake is the first name that comes to mind, and rightly so. Okay, so now I’ve mentioned him, but since I’ve already noted “Watch Your Back!” (Mysterious Press, 310 pages, $24.95) in this column, permit me to recommend “Groucho Marx, King of the Jungle” (St. Martin’s, 213 pages, $22.95) by Ron Goulart.

Mr. Goulart, one of the country’s leading authorities on pulp fiction, comics, and film, has written five previous books about the most famous Marx brother and his sidekick, former Los Angeles Times reporter-turned scriptwriter Frank Denby.

The series, which began with “Groucho Marx, Master Detective,” in 1998, is set in Hollywood’s Golden Age of the 1940s. Many mystery writers have employed this era to pay homage to the great noir films of the time, but that’s not the case here. There is absolutely nothing noir about these charming, lighthearted detective stories, which you will either love or hate.

If you think Groucho Marx was a funny man, you will have no choice but to giggle and chuckle your way through the books. The author has managed to write dialogue for the comic actor that sounds utterly authentic, which is to say it’s zany, nonsensical, frothy, and totally without respect for the corpse – or anyone else, for that matter.

Someone recognizes Groucho and says, “Oh, you’re one of those Marx Brothers.” He replies, “Two of those Marx Brothers, actually. Plus one of the Bronte Sisters.” The novel is filled with similar Groucho-isms, and if you don’t think they’re amusing, you should not read this book. You should, however, go out and see if there’s a cure.

Groucho and Denby arrive on the set of “Ty-Gor and the Lost City,” a Tarzan rip-off, only to find the star murdered. While those who had reasons to want him dead were legion, suspicion falls on a stunt girl who had had an affair with him.

Frank’s pregnant wife had asked him not to do any more detective work, so he asks Groucho not to get involved. “I’ll struggle manfully to curb my private eye impulses,” Groucho responds. “I’ll also try to curb my St. Bernard.” Lecherously encountering starlets as well as celebrities and autograph-seekers, Groucho and his sidekick, against all odds, solve the mystery for a nearly happy ending.

Also set in California near the outbreak of World War II is Rupert Holmes’s “Swing”(Random House,372 pages, $24.95). More serious and more stylish than Groucho (neither term has ever been applied to him anyway, as far as I know), Mr. Holmes has a sharp eye and a keen ear (or is it the other way around?). He also has the rare ability to describe a person with a single line that brands the character into the brain.

Jack Sherwood, the jazz saxophonist and arranger who is the first-person narrator of this wonderfully constructed and memorable novel, checks into a Bay area hotel and tells the reader that the clerk is “a pleasant enough young man, although it was clear he had no close relatives who were dentists or cosmeticians.” Later, at a snooty restaurant with a girl he hopes to impress, “the cafe’s only waiter approached Gail with a look of ennui he’d most likely received on graduation day at the Sorbonne.”

A young woman who dances in the Folies Bergeres approaches Sherwood and, although they had never met, asks him to marry her. She points out her excellent teeth, figure, and so on, but he decides to pass. A short time later, she plunges to her death from a tower.

The assumption is that, in desperation, she committed suicide: She was Jewish and destined soon to return to Vichy France, where her future looked as bleak as a January twilight in Siberia. But, this being a mystery novel, all is not as it seems.

The book is packaged with a CD of original big band music written by the vastly talented Tony-, Emmy-, and Edgar-winning Holmes. I urge you to swing by your local bookseller and bring a copy home.

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.