British intelligence has a deep penetration mole in the KGB. When that mole reports that a Soviet spy ring in London is no longer sending intelligence to Moscow, MI6 are worried. Catesby is sent on a mole hunt that leads him through the seamy sex scandals of 1960s London to the jungles of Vietnam. The tectonic plates of world power are shifting. The Whitehall Mandarin is set in a world of political and sexual ambiguity. Who can you trust?