Dean looks at Sam's corpse, laid out on a mattress. Bobby arrives with chicken but Dean says that he isn't hungry, and Bobby suggests that it's time to bury Sam. Dean refuses, and asks Bobby to cut him some slack. His friend says that he needs his help because something big is going down, but Dean says that he's given enough and yells at Bobby to get out. He quickly apologizes but asks Bobby to go. Bobby says that Dean will know where he'll be and leaves.
Jake Talley camps out in the woods and dozes off, and the Yellow-Eyed Demon appears to him in his dream. He congratulates Jake on being the last one of his children standing, and admits he didn't expect Jake to win. Jake vows to hunt him down and kill him, but the Yellow-Eyed Demon says that if he doesn't obey, he'll hunt down Jake's mother and sister and kill them. Cowed, Jake asks what he wants him to do.
Dean continues to watch over Sam's body, and wonders what he's supposed to do after letting down his father and his brother. He then drives off into the night and finds the nearest crossroads, makes a hoodoo box, and buries it at the center. A demon in a female body appears and says she's glad to see him. When he threatens to send her back to Hell, the demon says that he won't because he needs her to bring Sam back in return for his soul in ten years. She claims that she isn't interested and starts to walk away, and Dean asks what he has to do. The demon says that she'll bring Dean back and give him one year before she takes his soul. However, she warns him that if he tries to get out of the deal, Sam will die. He kisses her to seal the deal...
...and at the house, Sam wakes up. He checks his wound and discovers that he's completely healed. Dean comes in and embraces him, and Sam asks what happened. Dean claims that Bobby bandaged up the wound, and Sam vows to track down Jake and kill him. They eat and Sam explains what happened, and that the Yellow-Eyed wants the most powerful of its "children" as the leader of its army. Dean avoids telling Sam that he saved him, and wonders what the Yellow-Eyed Demon will do with Jake. He tells Sam to rest, but Sam is eager to get going. When he asks if Dean has called the roadhouse, Dean explains that someone burned it to the ground and killed Ash and the other hunters, and probably Jo and Ellen. Sam gets up to go find Bobby, refusing to rest like Dean asks.
The brothers arrive at Bobby's house, and he's surprised to see Sam alive. He play along with Dean and tells them that he's found demonic omens everywhere around southern Wyoming. There is one spot that looks like the demons have surrounded, and Bobby asks Sam to look it over while he asks Dean to come out with him to the truck. Once they're alone, Bobby realizes that Dean made a deal and demands to know how long he has. He grabs Dean and threatens to strangle him, but Dean points out it will only send him to Hell only. When Bobby wonders why Dean is so willing to throw himself away, just like his father, Dean points out that he was already living on borrowed time because of John's sacrifice, and he couldn't let Sam die. Bobby says that Sam will be torn up when he finds out, and Dean asks him not to tell. Before Bobby can respond, they hear someone moving in the junkyard. They grab the intruder and discover that it's Ellen.
Inside, Bobby has her drink holy water to prove she's the real Ellen, and she explains she was out getting pretzels when the demons attacked. Ash called her and told her to look in the safe, and by the time she got back, everyone was dead. She shows them what she got from the safe: a map of Wyoming. There are five 19th century churches surrounding an area, all built by Samuel Colt. There are private rail lines connecting each church, forming an enormous Devil's Trap. Sam figures that the lines are unbroken because the demons are circling the area but unable to get in. The only thing inside of the lines is an old cowboy cemetery right in the middle, and Sam realizes there's one thing that could destroy the Trap.
Jake drives up to the rail line and the Yellow-Eyed Demon arrives to tell him to cross over the lines and go to the cemetery. He hands Jake the Colt and explains it's the only gun that can kill him. Jake takes the gun and prepares to shoot him, but the Yellow-Eyed Demon says that he'll have nothing. However, if he follows orders, Jake and his family will have everything he ever wants, and they'll be royalty in the new world. Jake hesitates and then lowers the gun.
That night, he goes to the cemetery and approaches a mausoleum. but finds Dean, Sam, Bobby, and Ellen all waiting for him. Jake insists that he killed Sam, and says that Sam can't bring himself to kill him. He chuckles triumphantly and Dean wonders why, and Jake tells Ellen to put her gun to her head. She's unable to stop herself, and Jake explains that he's learned new powers now that he's given in. Ellen tells them to shoot, and Jake tells them to put their guns down. They do so and he runs to the mausoleum door and inserts the Colt barrel into the keyhole. While Dean and Bobby grab the gun from Ellen, Sam shoots Jake in the chest. Injured, Jake begs him to stop, but Sam ruthlessly shoots him down.
The door of the mausoleum opens on its own and Bobby tells them to take cover. A huge wave of demonic blackness shoots out of the mausoleum. Ellen explains that it's a Devil's Gate, a doorway to Hell, and they have to shut it.
The black cloud shatters the iron rail lines and the Yellow-Eyed Demon walks through.
Dean grabs the Colt and realizes that they can use it against the Yellow-Eyed Demon, but he arrives and telekinetically snatches it out of Dean's grasp, and then slams Dean into a tombstone. Sam, Ellen, and Bobby try to shut the gate, and Sam sees the injured Dean. He runs to his brother, but the Yellow-Eyed Demon telekinetically pins him down, and then pins down Dean. He thanks Dean, explaining that he needed Sam back and Dean obliged, and asks if Dean is sure what came back is pure Sam. The demon thanks Dean for sacrificing himself out of self-loathing, and prepares to shoot him. However, John emerges through the gateway and grabs the Yellow-Eyed Demon, pulling the black spirit essence out of the host body. The demon throws him aside and reenters the body, but Dean grabs the Colt and shoots him.
Bobby and Ellen close the gate, and turn to see John. He smiles at his sons and then fades away in a burst of golden light. Dean and Sam contemplate the Yellow-Eyed Demon's corpse, and Sam wonders if their father really climbed out of Hell. Dean figures he was stubborn enough to do it, but admits he doesn't know where John ended up. Sam doesn't know what to do now that they've avenged their mother's death, but Dean does: he tells the corpse that killing him was for killing their mother.
They go back to the Impala and Sam notes that Jake acted like he saw a ghost. He figures that Jake was right about killing him and asks Dean for the truth. Dean tries to avoid the question, but Sam demands an answer. His brother admits that he has a year, and insists he had to look out for his younger brother because that's his job. Sam asks what his job is, and says that he'll do whatever it takes to get Dean out of his deal. Bobby and Ellen come up and warn that they now have an army of demons to deal with. Sam and Dean go to the trunk, put the Colt in, and say they've got work to do.