professor baum introduces the case of dr. mabuse (rudolf klein-rogge), the criminal mastermind and hypnotist who ten years earlier went mad. mabuse spends his days frantically writing detailed plans for crimes while a criminal gang is committing them according to "the plans of the doctor", with whom they confer only from behind a curtain. when baum's colleague dr. kramm (theodor loos) by chance discovers that recent crimes implement mabuse's writings, kramm is shot by the gang's execution squad, hardy (rudolf schündler) and bredow (oskar höcker). a clue scratched in a glass window pane at hofmeister's crime scene causes lohmann to suspect mabuse. on arrival at the asylum, baum reveals that mabuse has died. when lohmann disparagingly talks about "mabuse the criminal", baum emphatically speaks about "mabuse the genius", whose brilliance would have destroyed a corrupt world.