Adam Humer was one of the most important members of the Department of Investigations in the Ministry of Public Security of Poland (MBP). This article presents Humer’s life and activity since his birth in the American city of Camden until he became the head of the Department of Investigation in the Voivode Office of Public Security (WUBP) in Lublin in 1944. The article describes his childhood and adolescence, with the main emphasis on his engagement in various youth organizations, mainly in Young Communist League of Western Ukraine. Following the chronology of events, the author then presents Humer as a student at the Catholic University of Lublin, and the reactions of his environment to the dissolution of the Communist Party of Poland and its political wings. The next part of the article includes Humer’s life after the outbreak of the Second World War: his communist activity in Tomaszów Lubelski in the autumn of 1939, his studies and endeavors during his stay in Lviv and after his return to the region of Lublin. The last part of this article describes Humer’s life after the Red Army entered Tomaszów Lubelski, including the electoral campaign to the National Council and his activity in the Communist movement.