Seven decades separate us from that tragic day when fascist Germany treacherously attacked the Soviet Union. The book of Professor B. Kovalev is devoted to a complex, contradictory and little-researched topic related to the Great Patriotic War. It presents a rich and unique material that reveals the panorama of real life and the motives of people's behavior under occupation: on the one hand, the origins of the mass heroism of the population caught behind enemy lines are shown, on the other, the reasons for cooperation with the invaders and betrayal. The book is designed for both specialists and a wide range of readers.