Truly a masterpiece of innovation being a film conceived on the cusp of the invention of sound included with cinema. Lang not only utilized the innovation of sound with the film but creatively crafted it with the narrative of the plot to truly being a level of innovation to the finely crafted screenplay that is M. Lang could have left it simple and let the cops be the good guys and be the only one on the trail of the serial killer but he added the aspect of the gang of the seedy underworld to be motivated by the killer as well which adds extra depth to the plot and transforms it from being a two dimensional narrative of good guys vs. bad guy, to more than that. Overall, when keeping in mind the limitations of this era, Lang truly crafted a fine piece of art.