In September or October 1973, the events of "Tinker Tailor Soldier Spy" take place, with Smiley successfully managing to expose Haydon as the long-term Soviet agent, or "mole", codenamed "Gerald" and reporting directly to Smiley's nemesis, Karla, head of Moscow Centre. Following the revelation, Alleline is drummed out of the Circus for his failure to identify Haydon himself and for permitting such a breach of national security to occur on his watch. Smiley is installed by Whitehall as the new head of the Circus and tasked with both tying up loose ends left by Haydon's treachery and launching a successful espionage mission to prove the organisation's viability.