"Infernal Affairs: Declassified Files of World's Double Agents" is a special-themed espionage storybook. The book focuses on a group of special spies who live among the enemy and use lies and deception to deal with the enemy every day. Sometimes they even lose themselves and don't know where they belong. Perhaps they were forced to make such a choice, perhaps they entered this world because they were greedy for money, or perhaps they came here out of the ideal of safeguarding justice. They walk on the edge of death every day and engage in "the business of licking blood with the blade of a knife." They are - double agents. This book selects 21 such top double-sided (or multi-sided) spies, including the famous "Cambridge Five" and the KGB spy king George Black, as well as the famous KGB traitors Rudolf Hermann and Levchenko. There is also the famous spy Vitali Yurchenko who defected repeatedly but managed to save his life; there is also the prototype of 007, the famous double agent Popov, the double agent Shevchenko who once served as the deputy secretary-general of the United Nations, and the spy Nick who led Stalin to launch the Great Purge. The Rai couple, and the double agent Brutis Cherniavsky who changed the course of World War II... Each of their stories is full of ups and downs, gripping, and sometimes makes us hold our breath... Let us feel the torment of truth and lies in their blood, tears, and love.