Supernatural Season 4 Episode 10: Heaven and Hell

Dean and Sam figure out why Castiel and his superior/handler, Uriel the Angel of Death, want Anna Milton dead when the three of them are forced to go on the run, not only from heavenly and vengeful angels, but from Alastair and his demon minions who also try to track down Sam, Dean, and Anna. With the assistance from the now-blind soothsayer, Pamela Barnes, they discover that 'Anna' is a fallen (former) angel and needs to seek her grace wings before the forces of both Heaven and Hell find them.