Normal, IL – 1958
A boy is sleeping at home, unaware that his father Henry is in the room watching over him. When the father tucks him in, the boy wakes up and his father tells him that he's going to work. When his son notices he has a pin with a symbol on it, Henry says that he'll tell him about it someday. Henry winds up his son's music box and tells him to go to sleep.
Henry goes downtown and knocks at the door of a house... a house bearing the same sign as on his pin. Josie Sands greets him in a dress and Henry admits that he wasn't aware the initiation was a formal affair. A servant calls her away and Henry hangs up his coat and sits down to wait. He hears screaming through the door and runs into investigate. There are bodies on a floor and another man is chanting at Josie. She grabs his throat and he says that it's impossible, while another man gives a box to Henry and tells him not to let Abaddon have it. Josie snaps the man's neck and screams, and Henry runs down the hallway to a workshop. Josie searches for him room by room as he desperately whips together a potion and draws a symbol on the door. It seals shut, preventing Josie's entrance, and the glyph he draws glows with energy. He leaps through and...
Henry finds himself in a motel room with Sam and Dean. He asks which one of them is John Winchester, insisting that time is of the essence. When they tell him that neither one of them is John, he wonders what he's done wrong. Dean grabs him and slams him against the wall, and demands to know what he's up to. Henry insists that one of them must know John and insists that violence isn't necessary. He apologizes for the misunderstanding and tries to leave, and Dean tries to handcuff him to the bed. They struggle and Henry manages to handcuff Sam and Dean together to the bed.
When Henry goes outside, he's astonished by all the changes from 1958. He checks the license plate on the Impala and confirms that he's in 2013. When the maid goes into the Winchesters' room, Henry breaks into the car but Sam and Dean capture him and take him inside. They test him with holy water and confirm that he's into a demon, and then demand an explanation. Henry says that they won't understand but when Dean says that John is his father, Henry realizes that he's in the right place.
The building starts to vibrate and Henry tells them to run. Josie emerges from the closet and tells Henry that he forgot to lock the door. She promises to kill them quickly if Henry gives her what he wants, and casts Sam and Dean aside with a gesture. Henry tries to get through to the Josie trapped inside, but the demon just laughs. Dean recovers and stabs her with the demon-killing knife, but she's merely stunned. Sam, Dean, and Henry run out and drive away. When the clerk runs out to yell at them, the demon breathes some of her essence into his body and sees what he's sees. She then rips his throat open and walks away.
The brothers drive out of town and pull over. Henry staggers out and throws up, shocked at the violence, and then explains that the woman was a demon, Abaddon, and he's from 1958. When he asks to talk to John, Dean tells him that John is dead. Shocked, Henry tells them that John is his son.
The brothers take Henry to a diner and he looks at a photo of him and his son. Meanwhile, Sam has checked his driver's license and questioned him, and is sure that he's really their grandfather. Dean points out that Henry left John alone and Sam suggests that Henry may have traveled to 2013 and got stuck so he couldn't go back. They join Henry, who is happy to meet his grandsons. Dean isn't happy to meet his grandfather, who John hated for abandoning him. They explain that they have a demon-killing knife but figure that they should send Abaddon back to 1958. Henry says that he used a blood sigil and will need at least a week to recover the power that he expended from his soul. When Sam says that only angels can do that, Henry asks how much they know and is surprised that John didn't teach them scholarly ways. When they explain that they're Hunters, Henry says that Hunters are apes and legacies.
When the brothers wonder what he means, Henry has them drive to Normal and takes them to the house but discovers that it's been replaced with a comic book shop. He realizes that it's a façade and insists that Hunters are crude shoot-first types. When Sam points out that they're John's children, Henry explains that he and his father were men of letters, and they passed on knowledge to a few select Hunters. Sam explains that they've never heard of them and Henry realizes that Abaddon is responsible.
Henry goes into the shop and figures that Abaddon wants the box, and attacked him on the night of his final initiation. He asks for a phone and tries to call an Elder, only to discover that the phone line is dead. They borrow the clerk's computer and run a check on the name of the Elders that Henry knows. Sam confirms that there was a fire at the gentleman's club that stood where the comic shop now is. Four men died in a supposed fire, and one of them was named Albert Magnus. Henry recognizes the name with satisfaction.
That night, the brothers drive to the graves of the four men. Henry explains that Magnus was an alias planted in the article so that someone recognizing the name would go to the grave. Three of the tombstones have the Aquarian Star on it, the Elders' crest. One tombstone belonging to Larry Ganem has a Haitian symbol on it instead and Henry realizes that's the clue.
Abaddon enters the comic book shop and reads the clerk's memories, including the cemetery's address. Once the clerk recovers, Abaddon says that she likes her top.
Sam and Dean unearth Ganem's coffin and check the corpse. He's wearing a medal with a name on it that Henry doesn't recognize, and he tells the brothers to cover it up and come with hm. They go back to the hotel and Henry whistles a tune that they recognize. He explains that when John was scared by a movie, he bought his son a music box that played "As Times Goes By." Sam checks John's journal and finds an entry referring to Abaddon as a Knight of Hell. Henry explains that the Knights are pure demons selected personally by Lucifer, and they suspect Abaddon is the last of her kind. Intrigued, Henry asks to see John's journal and discovers that it has his initials on it. He realizes he doesn't make it back to 1958 and Sam tells him that John never saw him again. Henry explains that he was supposed to raise John as a man of letters, but Dean tells him that John came up the hard way, losing his wife by a demon and then dying to another one later. Angry, Dean tells his grandfather that John kept going no matter what and did more good than bad. Henry wishes that he had been there for him but Dean says that it's too late and that his responsibility was to his family. When Henry says that he was a legacy and didn't have a choice, Dean doesn't believe it.
Henry pores through John's journal and then glances over at his sleeping grandsons. When they wake up the next morning, they discover that Henry is gone. He left a note saying that he's going to fix everything but Dean figures he'll screw things up.
Elsewhere in town, Henry goes to an apothecary and asks for ingredients for the blood sigil. The clerk says that she doesn't have them, but Henry says that she has Hunter signs in the winter. She draws a shotgun on him, and Henry renders her unconscious with a spell.
Dean checks the Impala and discovers that Henry stole one of the ingredients from the trunk of the Impala. Sam checks the computers and confirms that the police have found the clerk's corpse at the comic book store. Dean heads out to find Abaddon while Sam goes to Larry's address and meets with the old man and his housekeeper. Larry says that the Elders are destroyed and tells Sam that Abaddon was a hired gun. She killed the others and blinded him, but she didn't get the box. Larry tells Sam that the box holds a key to a library that holds the collected spells and scrolls of the Elders.
Dean finds Henry at the apothecary, casting the blood sigil. Henry insists on going back since he let down John, and Dean admits that he was wrong about what he said earlier. Dean warns him that he can't change the past, but Henry wants to give John the live he deserves.
Sam realizes that Abaddon wants the key so she can get hold of the library scrolls. Larry warns him that there's no way to stop Abaddon, and gives Sam coordinates where he can throw the key in so it is locked there forever. Sam isn't happy at losing all of that knowledge, but Larry says that it's the price they have to pay. Larry asks if Sam has the key and Sam says that his brother has it. At that, the housekeeper knocks Sam out and Larry realizes that Abaddon is there. She stabs him with a knife and then calls Dean on Sam's cell phone. She offers Sam in return for Henry and the key and tells Dean where she can find him. Henry insists that he can go back in time and stop it from happening, but Dean refuses to take the chance. When Henry casts the spell, Dean knocks him out.
That night, Dean drives to the address with Henry. When Henry wakes up, Dean tells him that he couldn't save John when he died. He doesn't want that to happen to Sam and will take any chance to save him. They go to the processing plant and Dean tells Abaddon to send Sam over while he sends Henry and the box. When Henry refuses to walk, Dean threatens to shoot him in the leg if he doesn't. Henry reluctantly walks forward, ignoring Sam, and Dean frees Sam. As the brothers try to leave, Abaddon seals the door and laughs. She then thrusts her hand into Henry's stomach, but he pulls a gun out and shoots her... just as he and Dean planned.
Abaddon laughs off the wound but discovers that Henry doesn't have the box. She tries to enter him and reads his memories, only to discover that she's trapped in the body. Abaddon realizes that the bullet Henry shot her with had a devil's trap engraved on it. Dean decapitates her and promises to cut her up and bury all the pieces in concrete. He then turns to the dying Henry and congratulates him, and Henry apologizes for judging them so harshly. With his dying breath, Henry admits that he should have known better and knows that having met them, he would have been proud of John.
The Winchesters bury Henry next to the other Elders and Sam says that now he knows what he meant when they were told that Heaven made sure the Campbells and the Winchesters intermarried. Dean shows his brother the photo that he found of their grandfather and father together, and wishes that John knew the truth about Henry saved them. Sam wonders if it would have made a difference to John if he had his own father around, and Dean figures that their father did the best he could.