The "Then" clips at the beginning of this episode gave us a look back at the episode where Castiel sends Dean back to see his parents when they were young, where he finds out his mother and her family were hunters and that she made a deal with the Yellow-Eyed Demon to save John. We also see some angel scenes with Castiel and Anna.
The "Now" section starts with Warrant's "Cherry Pie" playing and Dean saying, "I take it all back. I love the devil." Of course, the devil he's talking about is an exotic dancer dressed like a she-devil. But then she's joined by another dancer dressed like an angel. When the two girls step apart, there stands Anna. She's in his dream and tells Dean she can't find him. He mentions the thing Cas did so that he and Sam are invisible to angels. Anna responds, "Cas. There's a friend you can count on." She reveals that she's been in prison "upstairs" where there's "All the torture, twice the self-righteousness." She's not happy with Cas, who turned her in, saying he was always the "good little soldier." She tells Dean that she's broken out and to meet her at 225 Industrial, and to hurry. At that, Dean wakes.
Next we see Anna in an old building, and Cas shows up. He tells her that he wouldn't let Sam and Dean meet her and that if she's out of prison, it's because she was let out to do the angels' dirty work. Cas admits that it was a mistake to turn Anna in but he doesn't trust her sudden reappearance. When he questions her, she says that Sam has to die because he's Lucifer's vessel. Cas says they'll find another way, to which Anna points out that that plan isn't going so well. He tells Anna that he'll kill her if she comes near Sam.
Next, we see Anna fall on top of a sports car where a young couple is sitting. When they jump out to help her, we see a large Grease poster on the side of a building. Oh crap, I think she's just time traveled and I see where this is going.
Cas, back in the always-present crappy motel room with Sam and Dean, tells them of Anna's plan. When he performs a ritual to find her, he discovers she's in 1978. Cas figures out that Anna is going to kill John and Mary so that Sam can never be born. There's a bit of a funny moment when Dean makes a Back to the Future reference and Cas gives him a look and says, "I don't understand that reference." Against his better judgment, Cas takes Sam and Dean back in time with him. When they arrive, Sam and Dean are okay but Cas is coughing up blood. Dean checks Cas into the 1978 version of a crappy motel. When Sam asks if he'll be okay, Dean responds that Cas is "tough for a little nerdy dude with wings."
Sam is a bit freaked out at meeting his parents, especially his mom. But Mary is not thrilled to see them because she's left the hunter life behind. While she tries to convince them to leave, John gets a call from his boss, only it's Anna trying to lure him to work so she can kill him. When John gets to work, he finds his boss dead and Anna waiting for him. When the others arrive, big fight ensues. While Anna is distracted, Sam does that blood symbol on the wall thing to banish Anna. When John and Mary make eye contact, she knows her past has caught up with her. They all flee and go to an old house that has been in Mary's family for years and make preparations in case Anna shows up again.
It's odd, and so un-John-like, when young John expresses his disgust that anyone would raise their kids in the hunting life. Sam tells him that he used to be mad at his dad, but now he understands that he was doing the best he could in an impossible situation, that his dad might have gone crazy after Sam's mom's death if he didn't do something. Sam has a catharsis moment by telling this young version of his father that he understands and that he forgives him, that he loves him.
Anna calls Uriel and tells him that she needs him to kill some humans, humans who will kill him in the future.
When Mary asks Dean what is going on, he reveals that he's her son and starts telling her some of the future. He tells her what day she dies and tells her to take Sam and run that morning. Sam comes in during this conversation and says it won't work, that the demon will find her and baby Sam wherever she goes. He tells his mother that she has to leave John so that Sam and Dean are never born. Mary says she can't because she's already pregnant. John walks in and says that the symbols he drew are gone, and Mary discovered the holy oil is gone as well. Next comes the angel scream and the blowing out of windows. Another big fight ensues, in which Anna stabs Sam. A light appears on John, who has been tossed outside, and when he comes back in, the archangel Michael is inhabiting his body. He touches Anna and she goes up in flames.
Michael reveals to Dean that his being Michael's true vessel is in the bloodline, one that stretches back to Cain and Abel. In a true Dean moment, he says, "Awesome. Seven degrees of Heaven Bacon." Michael tells Dean that free will is an illusion, that every choice Dean makes brings him closer to his destiny, the plan that is playing itself out perfectly. He tells Dean that he is going to scrub John and Mary's minds, and the look on Dean's face is heartbreaking when he realizes his mom will still walk into Sam's nursery and still be killed by the Yellow-Eyed Demon. I did think that Michael's "You can't fight city hall" was a bit of an odd response. And then he heals Sam and sends him back to 2010, followed by Dean, who has an incredible look of "It's all for nothing" on his face.
Sam and Dean are back in the hotel when Castiel shows back up, looking worse for wear, surprised that he made it. Dean says he needs a drink, and Sam agrees. Dean looks at the three of them and dubs them Team Free Will -- "one ex blood junkie, one dropout with six bucks to his name, and Mr. Comatose over there. Awesome." Sam worries that the two of them will eventually say yes to being Lucifer's and Michael's vessels.
Next we see Mary, very pregnant, and John in the nursery, and Mary is happy about a 25-cent cherub she got at a garage sale and placed next to the crib. She tells the baby she's carrying that "angels are watching over you."
I was curious about the title of the episode, so I looked it up. It's the name of a concert film done by Led Zepplin in 1976 which includes each band member's personal fantasies (ties in with Dean's dream of exotic dancers and Sam getting to see his mother, and both of them wishing they could save their parents).