Oleg Gordievsky seemed to be the ideal product of the system - his father worked in the NKVD, his brother became an illegal KGB intelligence agent, he himself graduated from the elite MGIMO, joined the First Main Directorate, received the rank of KGB colonel. However, he worked for MI6 for more than ten years and became one of the key agents of British intelligence, who played a significant role in the history of the Cold War. According to him, he did it solely for ideological reasons. In The Spy and Traitor, based, among other things, on an interview with Gordievsky, British writer and historian Ben McIntyre tries to figure out what caused this man, so deeply rooted in the system, to rebel against it.