There is a lot to admire in any novel by Martin Cruz Smith, but nothing more than his deep understanding of what used to be the Soviet Union and is now a group of separate states with as much in common as Mozart and Britney Spears. His famous “Gorky Park” introduced police inspector Arkady Renko more than 23 years ago and became a classic of contemporary mystery fiction, In that splendid novel, the Iron Curtain was still up, Communism flourished behind it, and Renko had to orchestrate a dazzling performance to bring criminals to justice while avoiding the relentless interference of the party.

Now, in the excellent “Wolves Eat Dogs” (Simon & Schuster, 337 pages, $25.95), everything has changed. Or has it? Communism has been replaced by a system nearly as pernicious, with an overwhelmingly powerful mafia ruling (in all but official acknowledgment) Russia and other former Soviet states. Many of those who held power and wealth when all citizens were equal (well, yes, some were more equal than others) now hold even more power and wealth, since this is now legal and approved of in the New Russia.

As before, Renko must deal with a powerful, corrupt, and lazy bureaucracy, which proves to be as challenging as bringing the new crop of criminals to justice. Under the old dictatorship, a transgression could easily result in reassignment to Siberia. Today, failure to play along with the men in black, the criminal ruling class, can get one sent to Chernobyl, which is where Renko finds himself when he insists on investigating an apparent suicide.

The novel begins with a delicious conundrum. Why would one of the richest and most powerful men in Russia hurl himself from his 10th-floor apartment while carrying a salt shaker? The apartment is as secure as a gold brick in Fort Knox. The dead man, Pasha Ivanov, had become so paranoid that no one was allowed access to his rooms, not even his sexy 20-year-old girlfriend. After the sudden stop on the pavement after the plunge from his window, the police investigate, with everyone immediately accepting the notion of suicide. But Renko wonders about the clutched saltshaker and why there are 50 pounds of salt on the floor of his closet.

“Gorky Park” was set in Moscow, which is described as drab. “Wolves Eat Dogs” opens with the line, “Moscow swam in color.” It’s been just a bit over two decades, but there have been changes.

“Hazy floodlights of Red Square mixed with the neon of casinos in Revolution Square,” Mr. Smith continues in his description of what seemed, a few years ago, as improbable as a Yankee fan rooting for Pedro Martinez. “Light wormed its way from the underground mall in the Manezh. Spotlights crowned two towers of glass and polished stone, each tower capped by a spire. Gilded domes still floated around the Garden Ring, but all night earth-movers tore at the old city and dug widening pools of light to raise a modern, vertical Moscow more like Houston.” The majority of the investigation takes place in Chernobyl and its environs, and Mr. Smith paints a picture of this area too vividly to allow a comfortable night’s sleep.

“One way to look at Chernobyl,” he informs the reader, “was as a bull’s eye target, with the reactors at the center and circles at 10 and 30 kilometers. The dead city of Pripyat fit within the inner circle, and the old town of Chernobyl, for which the reactors were named, was actually farther away, in the outer circle. Together the two circles composed the Zone of Exclusion.”

“Wolves Eat Dogs” il lustrates the way of life in this zone, shockingly heavily populated with people who were evacuated but who returned to their apartments and their belongings. Even as researchers descended, huge numbers of poachers and scavengers ripped off anything of value and selling it to the unsuspecting, even as it practically glowed with murderous radiation.

Renko learns more about the zone’s environment and the survival techniques of its populace than he ever wanted to know. As he prepares to row to a rendezvous with someone prepared to sell information, he asks a local colleague, “How radioactive is the river?” “Water accumulates radiation a thousand times more than soil,” is the reply, “Oh,” he says. “But it settles to the bottom.”

So avoid the shellfish, is the advice. For that evening, Renko has been invited to dinner in a black village, so he intends to pay attention to the menu.

Only someone as stubborn, cynical, and melancholy as Renko would persist in an investigation that no one wants. Early in this case, which apparently involves high finance, he muses on his situation with frustration and resignation. “Arkady’s life had come to this: His highest skill lay in ferreting out which man had bludgeoned another. The subtleties of corporate theft were new to him, and he stood in front of the screen like an ape encountering fire.”

When his boss, Prosecutor Zurin, tells him to have his little look around and then go home and leave the case alone, he quietly balks. “And stop using the phrase ‘New Russian’ when you refer to crime. We’re all New Russians, aren’t we?” “I’m trying,” Renko replies, though it’s clear that, if he is, it’s an attempt as weak as instant decaffeinated coffee.

Whether or not you’ve read any of the other books involving Arkady, you should be rushin’ out to get this one.

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.