A cryptic, taunting criminal tells his targets exactly the number they are thinking of, even though they selected the digits randomly. A murderer walks away from a bloody corpse, leaving tracks in the snow that just end, leaving no evidence of how the killer escaped from the scene.

How can any true mystery lover, drawn to the genre for the chance to match wits with the author, resist straining his or her mental muscles to explain these apparent impossibilities? Both of these extreme challenges appear in the same book, John Verdon's astonishing 2010 debut, Think of a Number (Crown), a work that convincingly demonstrates that there's still life in one of the oldest mystery subgenres, the fair-play puzzle, by devising devious but plausible answers to baffling setups and fleshing out the framework with a fully realized and three-dimensional lead.

"Playing fair"—giving the reader a reasonable opportunity to solve the crime before the master sleuth reveals the truth—is a genre tradition that goes back to the golden age of detection, the period between WWI and WWII, when such books flourished. Back then, as Crippen & Landru publisher Douglas Greene puts it, "detective fiction was an elaborate and artificial entertainment, in which the writer set a gifted sleuth to solve a complicated crime—and every character was a potential suspect with hidden motives. The author gave all the clues to the reader at the same time as his fictional sleuth received them, and the reader was challenged to solve the crime before the author could spring his final surprise."

Most whodunit readers, even without knowing about the fair-play label, expect authors to abide by its principles; having the detective identify the killer as someone never referred to before in the novel, and based on research the sleuth did off-screen would strike everyone as cheating. Not that playing unfair is necessarily fatal to a mystery writer's success. In her August 16, 2010, New Yorker article, "Queen of Crime," Joan Acocella persuasively argued that, despite her role in popularizing the stagy but suspenseful denouement of assembling the suspects for the reveal, Agatha Christie didn't make it possible for her fans to work things out before Poirot or Marple did. And, unsurprisingly, few Sherlock Holmes stories gave the reader a chance to anticipate the Master. After all, they were intended to highlight Holmes's brilliance, rather than create a level playing field.

Notwithstanding the continued popularity of both Christie and Doyle, there's a lot to be said for a writer who takes pains to seed the story with information that an astute reader can piece together to correctly anticipate the outcome. The reader becomes more engaged because there is a reason to believe that close reading will pay off in the satisfaction of solving the case. In gifted hands, the concept of fair play allows for great creativity; the crucial clues could be in the contents of the dead man's pockets, the tone of voice used to recount an old memory, or a passing reference to a supporting character's professional background. John Dickson Carr, whose ingenuity allowed him to create dozens of locked-room or other impossible situations in the 1930s and 1940s for his sleuths to tackle that seemed to allow only supernatural explanations, was generally scrupulous about planting facts that would ultimately be vital to the solution. Carr was particularly adept at sliding clues past readers distracted by his Wodehousian humor. Perhaps the fairest of the fair was Ellery Queen, many of whose early novels featured a "Challenge to the Reader"—a page toward the end that unequivocally stated that the clues already presented are sufficient for a solution.

But with the rise of hard-boiled detective fiction, noir, police procedurals, and the plague of serial killers, the fair play has not maintained its primacy. Carr and Queen are not widely read today. Genre expert Otto Penzler believes the decreasing number of stories featuring pure detection is in part the product of time: "as years have gone by, an awful lot of motives, clues, methods, etc., have been used, so coming up with original material has become more and more difficult." Greene wonders whether the horrors of WWII and the reality that reason and justice do not routinely rule the day undercut the appeal of the restoration of the social order disturbed by bloodshed exemplified by the fair play.

But even before the inhumanity of the middle-to-late 20th century, few readers would have confused the artifices of the golden age with reality; rather, they would have found the intellectual puzzles, with a closed circle of potential suspects, and the assurance that the guilty would be brought to justice at the end, necessary, reassuring escapism.

It's not intuitively obvious why that need is any less today. And Americans still expect fair play in the mysteries posed by popular TV series, many of which incorporate a puzzle or puzzles into their story lines, that have inspired megabytes of online speculation as avid viewers share their reasoning and solutions in comment fields and chatrooms. Whether it's identifying the mole in CTU in 24, the Fairview strangler on Desperate Housewives, or unpacking what the island was on Lost, passionate followers of the shows analyzed, sometimes frame by frame, the evidence presented on screen, and were quick to howl if the final answer did not logically unfold from what preceded it.

And there are successful contemporary mystery writers, who adhere to the spirit of the golden age, even while abandoning artifice that may conflict with modern sensibilities. By moving away from focusing on the twisty plot, and peopling the stories with characters who have more emotions and personality, Jane Haddam, Peter Lovesey, and Louise Penny have breathed new life into the fair play.

Two decades after Haddam's Gregor Demarkian first appeared, he is still going strong; his 26th investigation, Flowering Judas, will be out this summer from Minotaur. Wanting Sheila Dead (Minotaur, 2010) does an especially artful job of misdirection; go back to the opening after learning the murderer's identity and you'll marvel at Haddam's facility in hiding the truth in plain sight. That deftness further bolsters those defenders of the fair play who note that they require that every word be processed, not just read. But there's much more to Haddam's work than just cleverness. She views the fair play as a form analogous to a sonnet: "The fair play is a skeleton on which all these other things, the characters, the stories, maybe a theme you're working with, go. If you do the skeleton well enough, it frees you to play all sorts of wonderful games with the rest of it."

Since 1991, Peter Lovesey has concentrated his efforts on the curmudgeonly Supt. Peter Diamond, blending modern police procedure with traditional pure detection. (The 11th, Stage Struck, is due from Soho in June.) Lovesey thinks that fair plays have evolved, rather than declined. "If you analyze many modern crime novels you'll find the placing and interpretation of clues are important elements. The fingerprints on the candlestick in the library are not so far removed from the spectrophotometry results that come back from the forensics lab. Thrillers and spy novels still rely on details slipped into the text and plucked out later like rabbits from hats to create surprise."

And while Louise Penny's Gamache novels (the seventh, Trick of the Light, is due in September from Minotaur) have an ever-growing passionate following for her mastery of the subtle interactions between people, and her gift at inventing characters her readers would love to encounter in real life, she has also managed to excel at hiding the truth in plain sight. By using psychological as well as physical clues, Penny manages the neat trick of having readers be stunned both by the disclosure of the killer's identity and by how they failed to anticipate it.

It's always risky to write off a long-established mode of storytelling such as the fair play. The limits of the subgenre are only defined by the limits of an author's creative imagination.

That it is harder to come up with a new variation on the impossible crime does not mean that writing one is itself impossible, as Verdon has proven. And Think of a Number's ranking near the top of several bestseller lists in Europe could presage similar status over here for his second book, Shut Your Eyes, due from Crown in July. While there's no reason to expect fair plays to return to their former prominence, fans of the golden age can still look forward to having their little gray cells exercised by murder puzzles, now presented in three dimensions. n

Lenny Picker is a freelance writer in New York City.