chunk: Smiley learns that Alleline, Haydon, Bland, and Esterhase have been meeting Polyakov—the "Witchcraft" source—at a safe house, where Polyakov gives them supposedly high-grade Soviet intelligence in exchange for low-grade British material, to help him maintain his cover with the Soviets. However, the mole is passing substantive material, including US intelligence, to Polyakov, his handler, whilst Polyakov's material has just enough substance to persuade the CIA to share information with the British.
  Smiley blackmails the location of the safe house out of Esterhase, whose exile status makes him vulnerable to deportation. Smiley then has Tarr appear at the Paris office, implying he knows who the mole is. The mole meets Polyakov at the safe house, where Smiley arrests him: he is Bill Haydon.