Counterintelligence is a complex art. In this book, a former employee of MI5 (British counterintelligence) introduces us to the intricacies of this honorable work. How to spot a rat in an organization? As a source of information leakage? How to protect your connections and personal secrets from strangers? In our time, when the average citizen is locked in the arms of surveillance by intelligence services, banks, the state, even his wife or mother - only knowledge of the basics of conspiracy can preserve our freedom and anonymity. We must value the freedom given to us and protect it. This book will give answers to many difficult questions and will help you hide from the all-seeing eyes of those who do not wish you well.