About Episode

The fallen angel Anna has escaped from her prison in Heaven and is planning on killing Sam in order to prevent the Apocalypse. She calls Sam and Dean and asks them to meet her, but instead of the brothers she encounters Castiel, who doesn't believe she has escaped but suspects there is something she is not telling them. Anna seems very evasive and disappears without revealing much of her plans. Later, Castiel meets up with the Winchesters and tells them that Anna has traveled back in time to stop Mary and John Winchester from conceiving Sam. The three also travel to the past, which weakens Castiel considerably. When knocking at their parents' door, Mary recognizes Dean from his earlier visit and tells them to leave immediately, suspecting something bad is bound to happen. John, however, is thrilled to meet "relatives" from Mary's side of the family and invites them in. Anna poses as John's employer and calls him at home, telling him to come to the garage he works at. After arriving there, he is attacked by Anna. The brothers and Mary come to rescue him, and Sam is able to drive Anna out of the building by using a magical sigil. They flee to a shelter, where Dean has a talk with Mary, in which he reveals that he and Sam are her sons and that she has to leave John in order to prevent her sons from being born. Suddenly, Anna and a younger Uriel rush into the house, attacking the Winchesters which allows Anna to kill Sam. Just as Anna is about to kill Mary, the Archangel Michael, having possessed John's body, enters the room and burns Anna to death. He reveals that Cain and Abel are the brothers' ancestors and that their destiny as Michael and Lucifer's true vessels has been set since those ancient times. He then revives Sam, erases Mary and John's memory and sends the brothers back to their time