While Dean sleeps the sleep of the angels, that sneaky devil Sammy steps out on him. Ruby picks him up in a shiny sports car, saying, "You ready?" Sam's face and voice are absent of all emotion save determination. "Definitely." They drive off into the night and are gone for the rest of the episode, because Jared Padalecki had to do some film work, and Sam and Ruby had to do their evil deeds in secret (what they are, I do not know, because SECRET).

With Sam out of the way, Castiel sends Dean back in time to Lawrence, Kansas on Monday, April 30, 1973, with only this cryptic instruction: "Listen to me. You have to stop it." Footloose, agenda-lite, and clueless in Lawrence, Dean stumbles into a coffee shop and the nice young fellow on the next stool -- the one who buys Dean a cup of coffee because he says he had a rough night -- is none other than Shut Up Daddy himself, John Winchester (decades before he needed to shut up). Later, Dean shadows John down the streets of Lawrence, but is intercepted by Castiel who again tells him, "You have to stop it," and then disappears. Castiel? You have to stop that. I know this stretches the imagination, but it's just going to make Dean even crankier. Swear.

Dean sniffs out John's trail later, and talks him out of buying a VW Van and into buying a 1967 Chevy Impala. Baby! Dean stalks John and Mary while they're on a date too, but the elder hunter knows when she's being tailed, even if her innocent date does not. Note the she and her. In 1973, Mary Campbell is a hunter from a family of same, and John wouldn't know a vampire if it bit him in the carotid. After she beats him up, Mary decides she likes Dean, but not that way because hey, she can take him -- so she does -- in to meet her folks, that is. Her dad, Samuel, is such an uptight grump, he makes modern day John Winchester look like a teddy bear. Her mom, Deanna, is fantabulous, and insists Dean stay for dinner. Grandpa Campbell is one of those hunters who works alone, drinks alone, and would probably die alone if it weren't for this episode's resolution. He fails to warm up to Dean, even when the latter is wearing his Father Whatawaste disguise -- which always works for me. After realizing a local boy made an unclear deal with the Yellow Eyed Demon (YED), Mary and Dean have a beautiful scene in which he tells her that he likes that John kid and that they're meant to be. They talk about John and her desire to leave the hunting life. When she says the worst thing she can imagine is her children being raised in the life like she was, Dean falls to pieces. Before he leaves her he makes her promise that on November 2, 1983, she won't get out of bed. She agrees. LIAR. When Dean (brandishing the Colt) saves a young woman in a neighboring town from making a life altering deal with YED, he earns Grandpa's respect and confidence. But Grandpa, unfortunately, gets possessed by YED, tries to get the Colt, and sniffs out Mary Campbell, too. He wants her to be one of the breeders of his own little master race of psychic kids to whom he'll feed demon blood ensuring they grow big and strong -- which certainly worked with Sammy. Dean can't get any information on YED's endgame, because this isn't Batman -- but it's much bigger than leading a demon army. YED kills Grandpa by stabbing himself in the stomach, and Grandma by snapping her neck like she's Jenny Calendar. Grandma Campbell is a pistol, by the way, she just can't get the pistol in time.

Still in the body of Grandpa Campbell, YED tracks down Mary and John, kills John who was about to propose, and makes a bargain with Mary moments before Dean gets there to stop her. The bargain gives John back his life, but YED won't extend it to her parents. She's too desperate to insist YED specify the terms of the deal beyond saying that in ten years, he'll need to swing by her house for a little something, but that as long as he's not interrupted, nobody will get hurt. Having lost her whole world in one evening, she agrees, and they seal it with a looooooooooong kiss, which is TOTALLY DISGUSTING, because YED's wearing her father's meatsuit, remember? Dean has to see it too, poor lamb, and he has to learn that he can't change destiny -- at least not that which has already occurred.

Back to the present: Castiel explains that they didn't bend time to give Dean a chance to stop YED, but rather to give Dean a chance to know everything they do. When Dean asks what he's talking about, Castiel merely nods towards Sam's empty bed, which gets Dean's attention right quick. Castiel says they know what Azazel did to Sam, they just don't know why -- they don't know his endgame. He tells Dean that Sam is at 425 Waterman and is headed down a dangerous road, and that they're not sure where it leads so he should, "Stop it. Or we will."

We fade to black with the nastiest three words in the English language splashed across the screen in brightest white: "To be continued…"