When the government finds out that a Russian mole has managed to infiltrate the innermost spheres of the British secret service, former spy master George Smiley is called out of retirement. He leads an underground investigation to smoke out and neutralise the mole. Smiley's contacts are impressive. His secret enquiries last several months, by the end of which he is able to shortlist four suspects. Te probables are codenamed Tinker, Tailor, Soldier, Spy.