This is the first complete book about the amazing story of Witold Pilecki. In 1940, he voluntarily went to the new concentration camp created by the Nazis, Auschwitz. Witold organized an underground network in the camp and for two and a half years secretly transmitted information about what was happening to the public. Thanks to him, the details and scale of Nazi crimes in the death camps were revealed to the world. The author carefully collected archival data and family sources, and conducted exclusive interviews with participants in the events. The result is a true but at the same time gripping story of heroism, resistance to the most terrifying circumstances and one man's attempt to change the course of history. Published in Russian for the first time.