Alan Furst has been writing novels about World War II for almost four times as long as the war lasted. Beginning with Night Soldiers in 1988, he has written 11 excellent espionage novels set during the war and the years leading up to it.

Long may he prosper. There may be no more sincere praise than to say that a writer consistently operates at a high level or even improves, since so often that is not the case. I have read the last six of Furst’s novels, and of them Spies of the Balkans (Random House) is the best, the most accomplished. It is not just readable, it is good reading, pulling the reader into a believable historical narrative.

Instead of proceeding chronologically, novels in the series lurch backward and forward within their overall time frame. The previous entry, The Spies of Warsaw, was set, not surprisingly, in Warsaw, from autumn 1937 through spring 1938. That was prior to the time period (1938-39) of the book before it, The Foreign Correspondent, about Italian émigrés in Paris.

Spies of the Balkans moves forward again. It’s October 1940 in the city of Salonika in northern Greece. Costa Zannis is a 40-year-old senior police official in an office handling mostly political cases. Salonika, a center of Balkan espionage for centuries, is now a crossroads of competing secret agents as the threat of German or Italian invasion nears. Zannis is temporarily called up as a reserve military officer when Greece goes to war with Italy in neighboring Albania.

This being a novel of intrigue, a fair amount of it naturally involves romance. When Zannis’ British lover, Roxanne, suddenly has to bolt the country, he is left with the surprised inference that she must have been a spy.

He also becomes involved, albeit not sexually, with a rich German, Emilia Krebs, operator of a kind of underground railroad to get Jews out of Germany. Both women will call upon him later for assistance, Emilia with refugees and Roxanne with facilitating the activities of the British secret services.

In between is a fling with an old flame, the sex-hungry Tasia, but when his glance happens to fall upon a Greek woman named Demetria, the unhappy wife of a pettily cruel multimillionaire, it is lust and love at first sight on both sides. Their romantic relationship amid peril is somewhat reminiscent of that of Robert Jordan and Maria in Hemingway’s For Whom the Bell Tolls.

While some novels are plot-driven and others are character-driven, Furst’s novels are both—but most of all they are atmosphere-driven. Graham Greene created “Greeneland,” a dim, dusty world of soured morality and languorous betrayal; just over the border is “Furstland,” a twilight realm of people on the run—refugees, Jews, leftists and others out of political favor.

Few have written as well about this aura of persecution and flight since Eric Ambler, master of sinister machinations in the shadowy byways of the globe, or, better yet, Erich Maria Remarque, who had personal, contemporaneous knowledge of it.

The author’s research, though it must be prodigious, is not obvious. His technique is to choose just the right seemingly inconsequential details to fill in the picture. For example, the jigsaw of citizenship and nationalities, natural and acquired (usually by purchase), is well put together. The sons of Zannis’ assistant, Gabi, buy Spanish citizenship. Everything is purchasable if you have the price.

The last three pages contain a couple of twists and surprises. Not fair to reveal just what, except to say the characters welcome them and the reader is likely to approve of them. One is brought about by S. Kolb, an enigmatic figure who also made brief but crucial appearances in Dark Voyage and The ForeignCorrespondent.

Spies of the Balkans does not go on to describe the devastation and plunder the Germans wreaked upon Salonika’s Jewish community, the largest in Greece. It ends in April 1941 just before their invasion. Perhaps it will be the subject of a future novel. We can only hope.

Alan Furst will read from his new book at 7 p.m. June 17 at Boswell Book Co.