Former intelligence officer Jim Prideaux (Mark Strong) readies his gun in the dramatic conclusion of Tomas Alfredson’s film adaptation of “Tinker Tailor Soldier Spy.”

At the top of the British secret service lurks a double agent, one who has been there for decades. Four men stand as suspects. There is Percy Alleline (Toby Jones), a bureaucrat who exudes sneakiness and craves power;  and Toby Esterhase (David Dencik), a nervous Hungarian whose ambition rivals Alleline’s; Bill Haydon (Colin Firth), a charming womanizer who has a shady web of informants; and Roy Bland (Ciaran Hinds), a stoic presence whose loyalties change on a whim. One of these men is passing information to the Soviet Union, and it is up to George Smiley (Gary Oldman) to find out which.

“Tinker Tailor Soldier Spy” —so named for the codenames of the suspects—is a film that demands the viewer’s complete attention. One moment of distraction and the spy thriller can leave you trapped in a web of confusion. However, Oldman’s steady comportment, along with a cast of actors whose extensive stage training and film careers have prepared them well, create not only an ambiance of suspicion faithful to the eponymous John le Carré novel but also an immersing thriller in its own right.

Oldman’s presence grounds the action of the movie. He embodies the role of stoic agent with infrequent shows of emotion that enhance his believability as a character. In one such scene, Smiley combs the apartment of his boss and old friend Control (John Hurt) for clues. When he finds a chess set in Control’s apartment with cut-out photos of the four suspects crudely taped onto bishops and rooks, the discovery of his own image on a fifth piece provides one of the most emotional moments in the film as Smiley’s normally composed visage briefly cracks with emotion at the discovery of his old friend’s suspicion.

There are only a few instances where a member of the sizable cast bursts into anger or tears, but the emotionally sparse nature of the film serves it well. As opposed to an explosive revelation of who the spy’s identity, the film ends with a single tear of emotion. In a movie whose action contains precarious chases, a subdued conclusion meshes perfectly with the equally guarded natures of its characters.

The supporting cast members play their parts with similar thoroughness, much as the characters they represent. The portrayal of each of the four suspects as they move in and out of the viewer’s suspicion ranges from Hinds’ under-the-radar glances to Firth’s bonhomie. Benedict Cumberbatch masterfully plays Smiley’s contact and compatriot in the service Peter Guillam. In one of the  most harrowing scenes of the movie, when Guillam  must steal logbooks for Smiley to analyze, Cumberbatch provides a fascinating alternation between a calm deportment around his fellow employees and a fearful tremble as he grabs the file, alone while contemplating the ramifications of being discovered.

But even with masterful acting of a cast trained in subtlety, a vitally important aspect of the film is the equally careful construction of 1973 London at the height of the Cold War. The gray, damp mustiness of Smiley’s house and the metallic, impersonal bunker of the British secret service combine with the sinister soundtrack composed by Alberto Iglesias in order to create a whirring, mechanical setting that is crumbling around the characters. The costuming, from Guillam’s immaculately tailored suits to Smiley’s  appropriately dramatic traveling coat, works as costuming should—extensions of the characters themselves. Director Tomas Alfredson strikes the perfect balance between attention to the outward appearance of the characters and the setting combined with internal elements intended only for the audience such as the gorgeously dark soundtrack.

Ironically, the one flaw of the film lies in the generally faithful adherence to the plot. The original novel includes all of the theoretical elements needed to create an interesting movie—spies, intrigue, the Cold War, and complex unraveling of characters’ psyches. However, while all of these elements are preserved, Alfredson’s truncation of them into an 120-minute performance requires a devoted attention that can become exhausting to follow.

However, despite this condensation, “Tinker Tailor Soldier Spy” approaches the depth of the first screen adaptation of the novel—a seven-part miniseries—while keeping the momentum of a two-hour feature. Certainly, it is a sin that the picture did not receive an Academy Award nomination for Best Picture as it deserves more recognition than a movie about a boy and his horse. It is the epitome of a film that demands the audience’s engagement with each moment, and the superb acting makes this an absolute pleasure.

—Staff writer Christine A. Hurd can be reached at churd@college.harvard.edu.