“Knock at the Cabin” has a dark and perverse premise, one of human sacrifice for the greater good. A group of zealots meet up and go to a cabin in the woods. Like in the movie ‘The Cabin in the Woods’, a similar sacrifice was meant to be made. The purpose was to save all of humanity. But in that movie, it would mildly poke fun at Horror Tropes. In this ‘Cabin’, the tone is dark and spooky, and the bizarre nature of the concept is not played for laughs.