Some people grew up on HARRIET THE SPY. I cut my cloak-and-dagger teeth on a grand literary tradition of high-class espionage fiction, from Graham Greene's THE THIRD MAN to John le Carré's THE SPY WHO CAME IN FROM THE COLD, from Len Deighton to Robert Littell and Charles McCarry. These books took spy novels away from the high moral ground and shadowy romance of Good Guys vs. Nazis or the racy, cartoonish high-jinks of James Bond; they evoked a gritty world of deceit and double-cross where both sides behaved in pretty much the same amoral, cynical fashion. Grim, textured and full of angst, they are spy stories for grown-ups.

THE TRINITY SIX  definitely partakes of this heritage --- there's even a sly reference to THE THIRD MAN --- and it also belongs to an espionage genre that might be called the mistaken-identity model: Someone who is not a spy is taken for one, or unwittingly possesses dangerous information, and is chased hither and yon (examples of this include THE THIRTY-NINE STEPS, the Bourne  novels, and the movie North by Northwest). Charles Cumming, author of three previous thrillers, has come up with a dandy protagonist, a London-based academic named Sam Gaddis. Sam has insider knowledge of the former Soviet Union --- his book, TSARS, compares Russia's anti-democratic president, Sergei Platov (Vladimir Putin?), to Peter the Great --- but otherwise he resembles a noncombatant traversing a minefield, with no clue about a spy's tradecraft (like how to lose a tail or save his skin).

His adventures begin with a mundane need for money: a giant bill for unpaid taxes and a demand from his ex-wife, living in Spain with their daughter, for private-school fees. TSARS isn't going to make him rich, and Sam is trying to conjure an idea for a bestseller when a couple of intriguing possibilities beckon. After a promotional event in a bookshop, an attractive young actress named Holly Levette tells Sam that her late mother was writing a history of the KGB and offers him the source material. (Bonus: He and Holly hook up.) Then, over a boozy dinner with a journalist friend, Charlotte Berg, Sam learns of her theory that in addition to the Cambridge Five, the notorious Soviet agents recruited at Trinity College in the 1930s --- Philby, Blunt, Burgess, Maclean and Cairncross --- there was a sixth member of the ring who has yet to be unmasked. A few days later, Charlotte is dead.

And not from natural causes, though this is not immediately apparent to Sam. He doesn't spend a great deal of time grieving, however. Soon, scenting a journalistic coup, he is hot on the trail of Charlotte's contacts, foremost among them an elegant, elderly trickster named Thomas Neame (one of Cumming's best creations, he would make a plum role for a British actor with Sir in front of his name if THE TRINITY SIX is ever made into a movie). Neame reveals that the sixth man's name is Edward Crane, that his death was faked, and that he is not only alive somewhere in England but has written his memoirs --- a manuscript that Sam, of course, is desperate to obtain.

But Neame, who is not altogether what he seems, doesn't make it easy for Sam. To betray too many of the secrets that pile up in this book would be to spoil the plot, which is THE TRINITY SIX's strongest feature. What I can say is that Sam is being pursued by both Russian and British intelligence (the Brit, Tanya Acocella, is yet another babe, not surprisingly; a whiff of Bond lingers). Wherever he goes --- Moscow, Berlin, Barcelona, Vienna --- there seems to be another dead body. Although Tanya bails him out more than once, Sam is a bright guy who gradually gets a handle on this spy stuff. It's a nice touch that Cumming allows some of Sam's academic skills to come in handy. Not only is he fluent in Russian, he's a pro at interviewing ("He was used to awkward conversations in cramped rooms. Students complaining. Students crying. Every  week at UCL [University College London) brought a fresh crisis to his office") and research (in pursuing the officially deceased Edward Crane, Sam "would, in effect, be looking for a man who no longer existed, yet that prospect did not unsettle him. Historians specialize in the dead"). Sam is smart, charming, likable and plausible, a hero you can root for.

However, the book seemed a bit facile to me. I do think there is an intellectual pleasure and gamesmanship to spy stories --- the reader attempts to penetrate the disguises the characters wear and puzzle out who's who and what's what --- but in the best of this genre there is also room for emotional depth. At bottom, these novels are about betrayal: wrenching violations of morality, patriotism and love. Because Cumming chooses subject matter that refers explicitly to an earlier period of espionage and espionage fiction, he provokes daunting comparisons to subtler, more psychologically acute writers like le Carré.

Apart from Sam and Thomas Neame, his characters are merely serviceable; the women especially are thinly drawn and unconvincing. And while the story, particularly his ironic ending, is satisfyingly twisty, sometimes he undermines the suspense by giving away too much information too soon. Finally, I think there's an excess of "tell" and not enough "show": In the early going, Cumming stacks up scene after scene wherein Sam attempts to extract information from key sources. The back-and-forth gets old fast.

But the pace does pick up as the book progresses. And the historical context of THE TRINITY SIX --- the way it resurrects the spy scandals of the 1950s and 1960s --- adds dimension and richness to the narrative. Cumming writes clearly, too; this is not one of those cryptic tales that requires a cheat sheet to follow the action. In fact, it is practically movie-script-ready. One man, two beautiful women; a series of brutal "eliminations" and heart-stopping chases; colorful multiple locations that call for a typed announcement at the bottom of the screen (BERLIN: 0500 HOURS). Could a film based on this book be the next The Bourne Identity or The Adjustment Bureau? I wouldn't be surprised at all. Now, if only Matt Damon had a British accent….