Supernatural Season 4 Episode 16 – On the Head of a Pin – Can torture be God’s work? After seven angels are mysteriously murdered, Castiel and Uriel demand that Dean use the agony-inducing skills he learned in Hell to extract information from Alastair. – Stream Supernatural Season 4 Episode 16 Online for Free – Watch Supernatural Season 4 Full Episode 16 Free – OnionFlix Official