Anna appears in a dream of Dean’s and tells him she is being held prisoner in heaven. When Castiel hears about this revelation he is immediately suspicious. He meets up with Anna and she tells him that in order to save the world Sam must die. Following this chat Anna is sent back in time to 1978, with a mission to kill John and Mary Winchester before Sam can be born. Sam, Dean and Castiel follow suit and manage to stop her from killing John. The boys come clean with their mother, and she responds by telling them that she’s pregnant with Dean. Anna and a younger Uriel soon arrive and Sam is wounded in the fracas; luckily Michael is on hand to kill Anna, banish Uriel and heal Sam. Before wiping John and Mary’s memories, he tells the boys that they are ancestors of Cain and Abel, and that Dean must be his vessel in the future.