Cold war thriller, based on the best-selling novel by John Le Carré, in which a semi-retired intelligence officer is assigned the task of uncovering a high-ranking Soviet agent within MI6. When British agent Ricki Tarr (Tom Hardy) discovers, courtesy of an affair, that there may be a Russian agent operating at a high level in MI6, it is clear that an investigation into the issue will be delicate matter. Enter George Smiley (Gary Oldman), an old hand in intelligence circles, and his associate, Peter Gulliam (Benedict Cumberbatch). The pair are assigned the task of tracking down the agent, but must do so under the radar of the MI6 leadership, for the very reason that they are all under suspicion...