A search for the one thing that may give the Winchesters an edge against God leads Sam and Dean to Jo's door and to a secret that may have died with Ruby; Castiel asks Jack to do the unthinkable to help the brothers in their quest.

Cast: Jared Padalecki, Jensen Ackles, Alexander Calvert, Misha Collins, Danneel Ackles, Lisa Berry, Genevieve Padalecki, William Vaughan