Among other themes, over his long, brilliant career John le Carré has examined the infinite permutations of betrayal, focusing most notably on the British Secret Services, a subject he often uses to symbolize the state of his nation, even the state of the West in general. His richest works concern the Cold War, in which various intelligence services fought their battles in the shadows and, as his novels show, very little separated the major antagonists in morality or conduct - each side willingly sacrificed the values it pledged to defend.

The screen adaptation of one of his most thoughtful books, "Tinker, Tailor, Soldier, Spy," demonstrates the ways in which the author approaches material that usually receives some version of the familiar blockbuster treatment. Set in the 1970's, the movie deals with the search for a mole, a Soviet spy in the highest circles of MI6, British Intelligence. As both history and le Carré instruct us, the usual spy is not some highly trained agent who infiltrates some level of the military or the government, but in fact a traitor within that organization who transmits information to an enemy.

At the request of a cabinet minister, George Smiley (Gary Oldman), who serves as the moral center of several of the novels, embarks on a quest to find the mole among the small group of men in charge of MI6. Previously squeezed out, along with Control (John Hurt), the head of the service, and a handful of others, Smiley conducts his own surreptitious research. He gathers information, not always legally, from classified files, interviews several former colleagues, and backtracks over a series of events that resulted in the shooting and torture of an English agent sent by Control on a special mission in Hungary.

As he proceeds through his arduous task, which provides the central plot of the picture, the people he interviews supply bits of information about the shooting incident in a series of flashbacks. Their stories reveal that the wounded agent, Jim Prideaux (Mark Strong), was betrayed by the mole that Smiley searches for, bringing him ever closer to a truth he suspected all along. His exploration of the past also becomes a painful personal journey, as virtually every step recalls to him his wife's infidelity, and he relives another kind of betrayal bound up with the actions of the traitor.

Appropriately for an author deeply committed to a kind of philosophical rather than merely physical approach to the intricacies of espionage and counterespionage, the film moves through labyrinths of understated dialogue and muted emotion. The subdued tone makes the moments of actual violence more shocking than the stunts and pyrotechnics of most motion-picture thrillers. The intercutting and parallel actions, the movement back and forth through time, never call attention to themselves, but appear naturally and absolutely seamlessly within the several narratives.

Typical of le Carré, the movie also suggests some unpleasant truths about organizations, institutions, and bureaucracies of any kind, showing the corruption and mendacity of the powerful and the consequent vulnerability of any individual with any integrity. It hints at Smiley's own doubts about the righteousness of his side, populated by people very much like the enemy, with a similar willingness to sacrifice anything and anyone necessary to accomplish their own dubious designs.

"Tinker, Tailor, Soldier, Spy" succeeds in many ways, for many reasons, not least because it is so satisfyingly an actor's movie. The only certified leading man in the cast, Colin Firth, occupies a relatively small role among an ensemble of character actors, whose faces and accents reflect a convincing reality, as if they were indeed the people they play. Although John Hurt, looking even more unhealthy than ever, turns a bit hysterical as Control, all the other actors display precisely the smug, sneering superciliousness of high-level bureaucrats and department chiefs everywhere.

The real triumph of "Tinker, Tailor, Soldier, Spy," however, belongs to Gary Oldman, who turns in an uncanny performance, speaking only rarely and precisely, demonstrating that the essence of acting is reacting. The history and outcome of Smiley's search, the heartbreak of his personal betrayal, even the ambiguity of his victory appear as subtle marks on his calm, passive countenance, allowing us to read the book of his pain.