By Guillermo Martinez

MacAdam/Cage. 197 pp. $23

It is easy to see why Guillermo Martinez's new mystery, "The Oxford Murders," has been picked up for publication in some 20 countries. Already a bestseller in the author's native Argentina, this tale of a mathematician's encounter with murder amid the dreaming spires of Oxford, England, has a great deal going for it: a winning narrator, quirky secondary characters and a well-drawn academic milieu. The narrative recounts the occurrence of serial murders perpetrated by a maniac with a mathematical bent -- and the imagination to tease a legendary logician with epistolary clues.

For those outside the English-speaking world, particularly those who see Oxford University as an exotic realm, the author's beautifully executed portrait of that place may more than make up for the novel's few but significant flaws. For those of us who are better acquainted with Oxford (if only through reading countless detective novels set there), some disappointments may tarnish this shining effort.

So much depends upon Martinez's appealing narrator. Like the narrator of Daphne du Maurier's 1938 thriller, "Rebecca," the graduate student from Buenos Aires who recounts what he calls "the Oxford Series" of murders is never named. He is endowed with a keen eye for the material world and his own emotions, a confidential tone of voice and a winning sense of wonder about the mathematical thinking central to this book. All these attributes work magic here.

We like our guide from the opening scene, where he confides, "I was twenty-two, an age at which almost anything can still be excused. . . . I was flying over the Atlantic in the incredulous state which overcomes me when I travel: it always seems much more likely, and more economical as a hypothesis -- Ockham's Razor, Seldom would have said -- that a last-minute accident will send me back to where I started, or to the bottom of the sea, than that an entire country and the immense machinery involved in starting a new life will appear eventually like an outstretched hand down below."

And who is "Seldom"? A luminary logician, Arthur Seldom is on the scene -- strangely agitated even before the victim is found -- when the narrator discovers his landlady, Mrs. Eagleton, murdered in her home. An elderly woman who whiles away her days by playing Scrabble solo, Mrs. Eagleton served as a code-breaker during World War II. Destined to die from cancer, she is the first in the series of victims who, while living on borrowed time, are robbed of their final days. If Seldom had not been alerted by mysterious messages, this and the other deaths might have seemed to be "murders that no one sees as murders . . . imperceptible murders."

As each crime is perpetrated, Martinez takes us into more worlds-within-worlds in and around Oxford. One consists of the tennis courts where the narrator makes "Love!" with his new girlfriend, Lorna. She's a redhead at least a decade his senior who's hot on the court and in bed. In the latter, she reads crime novels and a complicated treatise written by none other than Seldom. Lorna also works in the Radcliffe Infirmary, scene of the second crime.

Perhaps most memorable -- and threatening to the surprise element -- is the window Martinez opens on the interior worlds inhabited by mathematical minds. Seldom -- whose latest book on logical series contains a chapter on serial killers -- explains, "In the stingy logic of the economy of hypothesis a different logic prevails: why assume something strange and out of the ordinary, such as a murderer with intellectual pretensions, if they have more immediate explanations to hand?" Unfortunately, ruminations like this one may lead the reader too surely to the crime's solution. In another instance, bibliographic research leads to a revelation we'd much rather see reasoned out. Then, too, the police allow Seldom to break the news of Mrs. Eagleton's murder to her granddaughter, the chief suspect. That is a procedural gaffe that will leave any mystery fan laughing.

Still, the humor here is delicate and sound. Speaking to a suspect with an airtight alibi, Seldom says, "So you were consulting books at the time of the murder? For once, knowledge really is freedom."

In the last analysis, though, it is Martinez's descriptions of the mathematicians that buff the tarnish on this vessel: "Seeing them all together -- shy, untidy, polite -- I remembered Seldom's words. Yes, here they were, two and a half millennia later, queuing for their coffee in an orderly fashion, coins in hand, the ardent disciples of Pythagoras."

Dorothy L. Sayers herself could not have better characterized the denizens of a Common Room. This book may not win first-class honors, but those who love a mystery mixed with a portrait of academic life should not miss "The Oxford Murders."