Charlie contacts Sam and Dean after she finds the book of the dead - which could help eliminate the mark of Cain; Castiel and Metatron look for Castiel's grace. [...]
Dean and Sam investigate grisly, identical suicides by various people with little in common; the brothers begin to suspect that a priest is involved. [...]
A ghost is revenge-killing people; Sam and Dean discover who it is and why it is, but they can’t figure out how. With three dead, they must find out, and fast. [...]
Looking to get Dean out of the bunker, Sam finds a case for the two to investigate: People are disappearing into thin air with only their clothes left behind. [...]