In his fascinating new novel, “Defectors,” Joseph Kanon uses the tangled ties between two brothers to explore the world of espionage at the height of the Cold War. Kanon, the author of “The Good German,” and “The Prodigal Spy,” among others, is a master of the genre, and here delivers a book that will appeal to fans of “The Americans’’ and “Bridge of Spies.”

“Defectors,” by Joseph Kanon (Atria)

The plot follows the lives of Frank and Simon Weeks. Born a year apart to a prominent Boston family, they were students at Harvard in the late 1930s when Frank shocked his family and friends by leaving to join the Loyalist army and fight against fascism in the Spanish Civil War.

Wounded there, Frank returned to work in American intelligence during World War II. After the war, he joined the newly formed CIA. The brothers, always close, in those days would meet for lunch at Harvey’s, the most celebrated Washington restaurant of its day, to gossip about girlfriends, politics and their jobs. Then, in 1949, Frank, a rising star with the CIA suddenly flees to Moscow with his wife, Jo, because he is about to be exposed as a Soviet spy.

Simon becomes the editor of a New York publishing house. (Kanon is a former publishing executive.) In 1961, he receives an offer from the disgraced brother he hasn’t seen in more than a decade. Frank reports that his new masters at the KGB have given him permission to write a book telling why and how he became a spy. Simon thinks that such a book could be an international success and replies that he will publish Frank’s story if he will tell it honestly. Soon Simon flies to Moscow to work with his brother on the book’s final draft.

Simon is thus reunited with the charming, inscrutable older brother he still loves but doesn’t entirely trust. He sees that Jo, whom he remembers as young and vibrant — they were briefly lovers before she met and married his brother — is now depressed, drinking too much and close to a breakdown. The couple live comfortably in Moscow but they and other defectors are trapped in ambiguity. Officially, they are heroes for their service to communism but in truth they know they’re not trusted.

Simon meets Boris, the Soviet army officer who is Frank’s driver, bodyguard and watchdog. Even when Boris is not there, Frank and Jo know their home is bugged. We meet other defectors, both American and British; some are content and others miserable. One plump, genial woman is celebrated because, when she worked at the Los Alamos lab and was searched by a soldier, she successfully “hid the atomic bomb design in her hat.” Most of these defectors are fictional but real-life figures also appear. Guy Burgess, a member of the notorious Cambridge Five spy ring, for instance, turns up in a bar, drunk and bloated.

A quarter of the way through “Defectors,” the real story begins when Frank admits to his brother that he has more in mind than a book. He intends to defect again — back to the United States, where he hopes to be welcomed for his detailed knowledge of the Soviet espionage service. He says he will do this for his wife and because of his disillusion not with the theory of communism but with its reality. Frank knows that if this new betrayal fails he will be shot, and Simon will likely receive a show trial and a long prison sentence. The recent trial of downed U-2 pilot Francis Gary Powers is cited.

Frank’s plan to escape the Soviet Union is immensely complicated, but its unfolding is enhanced by Kanon’s graceful writing. When Simon attends the Bolshoi Ballet (to pass a message to an American spy in the men’s room during intermission) readers receive this unexpected gift:

The author Joseph Kanon (Chad Griffith)

“He had always assumed Swan Lake was kitsch, a ballet for tourists, but here it meant something else. There was a fluttering of white, the entire stage suddenly twirling with white, darting, floating. A quiet gasp went through the audience, a collective pleasure, everything as it should be, the precise toe steps, the graceful leaps, inexplicably beautiful, the dreary city falling away, mad Stalin in his side box, the brutal prison stories, lives with years snatched away, all of that gone now, out of sight, nothing visible but this twirling, what the world would be like if it were lovely.”

Such passages make “Defectors” as readable and suspenseful as the fine espionage novels of Eric Ambler, Graham Greene, Charles McCarry, Robert Littell, Alan Furst and John Le Carré — and its roller-coaster plot will keep you guessing until the final page.

Patrick Anderson regularly reviews mysteries and thrillers for The Washington Post.

Defectors

By Joseph Kanon

Atria. 290 pp. $27