Dread throbs like a heartbeat in “Tinker, Tailor, Soldier, Spy,” a superb new adaptation of the 1974 spy novel by John le Carré. It’s a deep pulse that maintains its insistent rhythm throughout the film’s murmured conversations, life-and-death office intrigues, violence and yearning loves. The throbbing does a number on your nervous system — this is a movie you watch on high alert — and brings you into the state of mind that can feel like a state of siege and goes by the name of British secret service, or just the Circus. For those inside the intelligence service, like George Smiley, played with delicacy and understated power by Gary Oldman, knowledge is power, but so too is fear.

The story, skillfully mined from Mr. le Carré’s labyrinthine book and set in 1973, is a pleasurably sly and involving puzzler — a mystery about mysteries within mysteries. The head of the service, known as Control (John Hurt), believes that there’s a Soviet agent, a mole, among the agency’s elite. His main suspects include his closest aide, Smiley, along with Percy Alleline (Toby Jones), Toby Esterhase (David Dencik), Roy Bland (Ciaran Hinds) and Bill Haydon (Colin Firth). To find the mole, Control secretly sends Jim Prideaux (Mark Strong), who runs the agency’s scalp hunters (field agents with dirty, sometimes bloodied hands), to Hungary to retrieve information. But Prideaux, in an agonizing botch-up, is shot, and Control, already politically weak, is fired along with Smiley.

Mr. le Carré’s seventh novel and the first in his Karla trilogy, “Tinker, Tailor” is set against a geopolitical (and movie) moment that is almost quaintly, reassuringly old-fashioned, a time when enemy agents had names like Boris, and a red flag with a hammer and sickle made the ideological and political stakes clear. It’s a world of secrets and lies, shadows and light, illusions and sordid truths, loyalties and perverse betrayals (it could be called “Enemies, a Love Story”) that the director Tomas Alfredson conjures up in the film’s uneasy opening in Control’s apartment, a cluttered warren fogged over by cigarette smoke. “There’s a rotten apple,” Control says to Prideaux, drawing on a cigarette as he explains his theory about the mole, the folds in Mr. Hurt’s magnificent face sagging a bit lower.