The document discusses the director Fritz Lang's use of the character Hans Becher to portray insanity in his film M. Lang shows how Becher's insanity spreads among the city's residents, causing them to challenge authority and turn on friends. Becher's outward normal appearance hides his unstable mental state. Scenes depict his worsening mental state through his facial expressions and the unsettling objects in shops he visits, symbolizing his mental decline.