The plot isn't easy to summarize, but I'll give it a shot. Bill Cage is a former newspaperman, now a PR flack. When he was young, he read widely and deeply in the spy fiction field, and his father, an American diplomat was a collector of first editions (Cage, too, collects them). Cage hasn't read any spy fiction in the last 20 years, but the books he loves and remembers are the same ones that I was reading at about the same time Cage was. The good stuff. Fleming, Deighton, Ambler, Greene, Hamilton, and on and on (there's a nice appendix that lists the books in the library of Cage's father).
Thing get started when Cage gets a mysterious note that welcomes him to The Double Game. He's easily sucked in, and the game is of course espionage. There's an old secret that even the CIA has never quite come up with an answer to, and someone's using Cage to find out. Cage returns to Europe, where he grew up, and is put through his paces in many of the cities he's familiar with both from spy fiction and because he lived in them as a boy. The clues he gets are all based on books he's read, and many familiar novels are quoted or referred to. For added fun, one of the characters is a book scout, and several bookstores get visited. Real characters you older folks will be familiar with from newspaper stories about the Cold War are mixed in with the fictional ones.
As it turns out, there are a lot of secrets besides the big one. Cage is reunited with the woman he'd loved as a teen. Is she on his side? His father is clearly keeping things from him. So is everyone else he meets.
A twisty plot, neat settings, books (lots of books), rekindled romance, fathers and sons, slimy characters, tradecraft, danger, and all the other ingredients. The story's also told in a fluid, engaging style. Thoroughly enjoyable.