It's a few days before Halloween and Sam (Jared Padalecki) and Dean (Jensen Ackles) 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 (guest star Misha Collins) arrives in town and tells Sam and Dean 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) to smite the entire town.