While sorting through his late father's estate, Swedish Torkel Wächter uncovers a series of letters from Nazi Germany that he doesn't understand. They tell the story of a man named Walter, a talented footballer who once played for famous Hamburger SV and was later imprisoned in a concentration camp. Driven by a personal quest for truth, Torkel Wächter embarks on a years-long investigation that ultimately reveals the hidden identity of his own father. The film portrays his moving journey back into the Nazi history of HSV, from football matches among prisoners in concentration camps to the present day. This sports documentary confronts the darkest chapter in German football history.