In the movie, an espionage veteran named George Smiley, played by Gary Oldman, comes out of retirement to help uncover a Soviet mole working in Britain's secret intelligence service.
"George is someone who wants to anonymous. He wants to blend in. He wants to disappear. That's what makes him so dangerous," Oldman said.
"Tinker Tailor Soldier Spy" is a complicated film - one that will require your full attention. And Oldman wouldn't have it any other way.
"I think it's nice in this day and age that a movie does not undermine the intelligence of the audience, and that you have to come in and you have to work a little bit and you have to listen," he said. "I think it's quite refreshing, rather than this sort of dumbing down and just a wall of imagery and sound coming at you."
Colin Firth, who has a supporting role in the film, echoed Oldman's sentiments about the movie's complexities.
"If understanding the details is what you're after, it will help to read the book," Firth said.
The film is now part of the competitive holiday season at the box office, but Oldman is hopeful since it's already been doing extremely well in Britain.
"That tells me that there's an audience for this kind of thriller," he said.
"Tinker Tailor Soldier Spy" is rated R.
