Geoffrey Prime was a Soviet spy throughout the most intense years of the Cold War. The linguist served his paymasters for almost fourteen years and became the most important Russian mole in British signals intelligence since German Enigma decryptions were leaked from Bletchley Park during World War Two. Recruited while serving in Berlin with the Royal Air Force, he became uniquely placed to betray his country's innermost secrets when he later obtained employment at the nerve-centre of government communications, GCHQ. By various clandestine methods of transcription and meetings overseas with his controllers, Prime divulged information on a massive scale until shortly before his arrest. His eventual downfall lay in an inability to control his lust for pre-pubescent girls and the conscience of a wife unable to live with the knowledge that her husband was not only a child molester but also an espionage agent. This is an involved story of debased morality and dishonour, siezed upon by an unscrupulous regime to its own advantage, and unearthed by unsuspecting provincial detectives in a tale of a police investigation on an unprecedented scale.