The 50 years leading up to the fall of the Iron Curtain in 1989 could be considered the golden age of espionage. As for novels written during that time, the Cold War category pretty much belongs to men: John Le Carré, Ian Fleming, Len Deighton, Robert Littell and Charles McCarry being the best known. And while spy novels set during the period continue to be written and read, men still dominate the field. I find that odd. But now here is Beatriz Williams with "Our Woman in Moscow," part spy thriller, part romance and, taken as a whole, a tale of two indomitable women.

Set between 1939 and 1952, it is the story of twin sisters, Ruth, a fashion model, later modeling-agency manager; and Iris, an aspiring artist. Their brother, Harry, works for the U.S. State Department and is stationed in Rome, where the two young women join him in 1939.

Ruth continues to model, and Iris haunts the city's museums, where she meets Sasha Digby, a mesmerizing, blue-eyed, golden-haired colleague of Harry's. An affair ensues, war rumbles closer, and Ruth arranges for passages on a ship to take them back to America.

But Iris has fallen pregnant by Digby, who turns out to be a boozer, philanderer and open admirer of the Soviet Union. Defying her sister, Iris stays on. In 1948, now married and a mother of two with another on the way, she and the children accompany Digby when he defects to the Soviet Union. He has, as we have guessed all along, been passing on intelligence to the Soviets.

We have learned much of this in retrospect from 1952 when Ruth hears from Iris who, despite previous dangerous pregnancies, is about to give birth again. Though the two have been alienated, Iris wants Ruth to come to her in this, her hour of need. Ruth arrives accompanied by one Charles Sumner Fox, an attractive, big-shouldered FBI agent posing as her husband.

Meanwhile in Moscow, we run into some unsavory characters including Guy Burgess and, more deadly, a KGB functionary and nasty piece of work called Lyudmila. She is a true believer so wedded to the Party that she has informed on her own husband. Now she is trying to track down a Western spy who is sending intelligence to London and begins to zero in on Digby who, it seems, may be a double agent.

Duplicity abounds and just what the main characters are really up to is not what it seems. The pace picks up and the plot races into white-knuckle territory. If "Our Woman in Moscow" does not rise to the diabolic heights — or terrifying depths — of many novels in the field, it is a fine entertainment with, as it happens, a kindly heart.

Katherine A. Powers, a Minnesota native, also reviews for the Wall Street Journal and the Washington Post.

Our Woman in Moscow
By: Beatriz Williams.
Publisher: Morrow, 448 pages, $27.99.