Dean is enjoying the company of two strippers when the angel Anna arrives to interrupt his dream. She admits this is the only way to contact him since he’s branded against demonic and angelic detection. When he wonders where she’s been, Anna explains that she’s been imprisoned in Heaven since Castiel’s betrayal. She managed to escape and warns that the other angels are on her trail, and then gives Dean her location.
When Anna arrives at the warehouse location, Castiel is waiting for her. He explains that he came to make sure it was safe, and points out that it’s impossible to escape imprisonment from Heaven unless the angels let her escape. When Anna points out that he’s the reason she was imprisoned, Castiel admits that he made a mistake. However, despite her claims that she wants to help, Castiel points out that she’s carrying a knife that will only kill mortals. His knife can kill angels, and he’s prepared to use it. Anna finally says that she plans to kill Sam and scatter his ashes so Lucifer can’t resurrect him and use him as a vessel. Castiel refuses to let Sam die, saying there must be another way. However, Anna points out that his attempts to use the Colt and find God have all failed so far. When he refuses to yield, she teleports away.
Two hippies are smoking pot in their car. Anna suddenly falls out of nowhere and lands on their hoods. She’s badly weakened and the hippies take her to the hospital… walking by a 1978 poster for the premiere of the movie Grease
Castiel returns to the brothers’ motel and prepares a ritual to summon Anna. He insists that the only way to stop Anna is to kill her, but Sam wonders if she’s right to kill him. Castiel discovers that she’s traveled back in time, to the year 1978, and that since she can’t get past him, she’ll kill John and Mary Winchester before Mary gives birth to either brother. Dean says that they need to back with Castiel, but the angel warns that he’ll be too weakened if he takes them with him. They insist and Castiel reluctantly agrees.
Sam and Dean arrive in the past. They avoid being run over, confirm that they're in 1978, and find Castiel nearby, all but dead. After checking him into a hotel's honeymoon suite to recover, they steal a car and drive to their parents' house. Dean comes up with a plan and they introduce themselves to John and Mary. Mary recognizes Dean from his last visit and isn't happy to see him. They claim that they're her cousins and Sam is fascinated to meet his father. John invites them to supper over Mary's objections. While they talk, John takes a call from his boss, Woodson, who says that he's been fired. John asks for a second chance and Woodson agrees to see John that night and give him a choice. However, John is unaware that Anna is impersonating Woodson's voice over the phone. He leaves for the garage. Meanwhile, Sam and Dean tell Mary that they are there to stop an angel from killing her and John. She realizes that she needs their help, but they discover that Jon has left.
At the garage, John finds Woodson's corpse, its eyes burn out. Anna attacks him and closes in for the kill. He tries to fight back without success, but Dean attacks her with the magic knife. She throws him through a window but Mary grabs the knife and attacks the angel. She manages to land a blow but Anna quickly defeats her as well. However, Mary has bought enough time for Sam to complete an angel banishing ward and send Anna away for the moment.
The brothers get their parents away and John wonders how long that they've been fighting monsters. Mary finally admits that she and her family are hunters. They go to a safe house that Mary's family has prepared and the brothers use sigils and holy oil to ward the place against angels. John insists on helping. When Dean warns that they need human blood to make the sigils, John cuts himself to provide the blood and Dean notes that he reminds him of his father.
Sam talks to John and apologizes for dumping too much on him. When Sam explains that his father raised him to be a hunter, John wonders how any father could do that a son, and how it could twist anybody's mind. Sam says that used to hate his father for doing that, but now he's realized that his father died protecting his sons and he understands that his father did the best he could. Sam tells John that his father needed something to occupy his mind after his wife died, and that Sam understands and forgives him.
Anna finds the house and summons the Uriel of 1978. He quickly realizes that she's from the future, but she reminds him that she's still his superior and he has to obey. Anna offers him the chance to take revenge on the people that will kill him in the future and he gladly agrees to help.
Mary demands answers from Dean, who finally explains that he traveled back in time from 2010 and that he's her son. He tells her things that only her son would know, and finally admits that the Yellow-Eyed Demon will kill her and John becomes a hunter to get revenge. Dean suggests that she run with Sam on the day that the Yellow-Eyed Demon kills her, but Sam overhears and figures that the demon will find and kill her no matter what. They suggest that she leave John now before Dean is conceived, but Mary admits that she's already pregnant.
John comes in and tells them that the sigils and holy oil have disappeared. The windows shatter and Uriel and Anna enter. Sam and Dean attack them but are quickly tossed aside. John grabs the demon-killing knife and goes at Anna, but she throws him through a window where he lies dying. Next she rips a pipe out of the wall and impales Sam with it.
As Jon breathes his last breaths, a golden light appears around him.
Anna prepares to kill Mary but "John" comes in and explains that he is Michael in a host body. Michael touches Anna and destroys her, burning her to ash. Uriel apologizes to the archangel, which sends him back to Heaven with a gesture. Michael then renders Mary unconscious with a touch and tells Dean that they have to talk before he heals Sam. He explains that John gave him permission to enter his body in return for saving Mary, and that he can enter the chosen body of any member of the bloodline, going all the way back to Cain and Abel. Dean tells Michael he won't help him satisfy his personal grudge against his brother, Lucifer, but Michael explains that he loves his brother. He doesn't want to kill Lucifer, but he has no choice. When Dean insists that God is wrong, Michael insists that everything is going according to God's master plan and Dean will ultimately say yes and give Michael access to his body. However, he won't leave Dean a drooling hulk like the demons do after possession, and he'll wipe John and Mary's memories so they don't remember what happened here. Dean says that Mary will be killed as a result, just as she did originally, but Michael notes that Dean always knew that would happen. The archangel heals Sam and sends him back to 2010. As he sends Dean back, he tells him that they'll meet again.
In 2010, Castiel manages to return to the present but collapses after arriving in the motel room. The brothers have a drink and Sam wonders if everyone is right and he'll eventually say yes to Lucifer. Dean wonders as well, noting that their father agreed to save Mary, and they might receive the same offer.
In 1978, John and Mary put an angel sculpture up in the nursery above their baby's future crib. She feels Dean kick and assures him that he'll be okay, because angels are watching over him. Share this article with your friends