The brothers deduce a witch is sacrificing people to summon a dangerous demon. Robert Wisdom ("The Wire," "Prison Break") guest stars as Uriel, a specialist angel.

A few days before Halloween, Sam and Dean investigate two mysterious deaths in a small town. The brothers find hex bags and deduce a witch is sacrificing people to summon a dangerous demon named Samhain. Castiel (recurring guest star Misha Collins - "24," ER") arrives in town and tells Sam and Dean that the freeing of Samhain is one of the Seals that will lead to freeing Lucifer, so Castiel has brought a specialist angel named Uriel (guest star Robert Wisdom - "The Wire," "Prison Break") to smite the entire town.