An old man, Daniel Elkins, sits scribbling in his journal, in a bar in Manning, Colorado. After leaving the bar in a hurry, Elkins is confronted by the woman, Kate, leading the group he saw earlier in the bar. Elkins attempts to load an old 5 shot Colt however after a struggle, he is murdered.

When Sam and Dean read about Elkins death, Dean recognizes the name from John's Journal. Arriving at Elkins' cabin, the boys find it ransacked and in chaos. Amongst the wreckage Dean finds a journal, a lot like their father's, and also a message. A mail drop, just the way their father does it.They find a letter addressed to "J.W.". They are startled by the surprise appearance of their father. Reading the letter, John realizes that Elkins had been holding out on him about a legendary gun, a Colt made in 1835. He tells them it's Vampires, and they will hunt them together.

Sam is bridling at John’s dominating attitude and is constantly questioning his father's orders. Dean is frustrated by the reoccurring old arguments that drove the family apart. Working together to attack the Vampire nest and look for the Colt, they are discovered before John can grab the gun, and end up running for their lives. John has alternative plan and while waiting for Dean to return with dead man’s blood, Sam and John talk, mending fences in the process.

They use the dead man’s blood to catch Kate in order to draw out Luther, her Mate. John’s plan is to trade her for the Colt. While Luther and his vampires discover John and Kate and parley for the Colt, Sam and Dean invade the nest,  freeing the captives. John’s plan is foiled and he is knocked out by Luther, however before Luther can kill him, Sam and Dean attack, having ignored their father's orders to stay away. John, grabbing the Colt, kills Luther by shooting him in the head. The gun works. It can kill supernatural beings with a bullet. Finally seeing the sense of the boys argument, John agrees that now they have the Colt, they will hunt the Demon together.

Blue Earth, Minnesota – A priest is reading the Bible at his Alter. Meg enters as a young woman seeking solace. The priest encourages her to speak but, when he sees her black eyes, the priest retreats in horror to an underground office. She demands the Winchesters who he refuses to betray. She slits his throat.

Back in Manning, Colorado, John is sharing his research of the last 20 years with Sam and Dean. John sees the signs starting again and is intent on saving another family from the pain and loss suffered by the Winchesters. The 3 hunters head out to Salvation, Iowa. On the road, John receives the news that Pastor Jim Murphy has been murdered. John feels the pressure to hurry, to find the next family on the demons list. Following the signs in his vision, Sam meets the young mother Monica and her daughter, Rosie. Unable to warn her, he returns to Dean and John. Sam’s phone rings and Meg, demands to speak with John. Informing him that she murdered Jim Murphy and today she is with Caleb. She wants The Colt.In desperation John plays dumb and Meg kills Caleb. John offers her the Colt, but he has a plan. To substitute a fake colt for the real one. 

 While the boys stand watch over Monica and her family, John confronts Meg. She is joined by another demon. John hands the gun to Meg and she in turn hands it off to the other, asking if they think it’s the real thing? Without warning he shoots Meg. Now it is obvious the gun isn’t the real Colt. Making his escape John finds his truck’s tires have been slashed. Running, he finds himself in a dead end and trapped.

Meanwhile, recognizing the signs, the boys break into the house in attempt to save Monica and Rosie. Racing to the nursery Sam faces the demon over Rosie’s crib a, fires off a shot but the demon vanishes. They race them from the burning house. Dean stops Sam from trying to reenter the burning building to reach the demon. Back at the hotel room, Dean tries his father’s phone, it is answered by Meg and to their horror she promises they will never see their father again…

The boys arrive at the home of another hunter, Bobby. Sam goes through some of Bobby's books on demon lore, including the Key of Solomon, while Bobby and Dean talk. Suddenly Meg kicks in the door, attacks the boys, and demands the Colt. However, she soon gets caught under a devil's trap that is painted on the ceiling. Bobby explains that Meg is actually a girl possessed by a demon, and that the injuries she previously sustained in Chicago (in the episode 'Shadow') will kill her if the demon leaves her body. Dean insists on exorcising the demon to save the girl, no matter how broken she is. Finally, the demon is banished, and human Meg, dying painfully, thanks them and offers the clue "sunrise." 

They arrive at the building where John is being kept, form a plan to evacuate it that involves dressing up as firemen, and execute it. They manage to overpower the possessed humans guarding John and get him out of the apartment - after Sam insists on testing John with holy water. John is barely coherent, but he manages to ask about the Colt. Once all three are out of the building, they're set upon by Tom, who beats Sam severely. Dean whips out the concealed Colt and shoots him through the head.

In a secluded cabin, the boys salt the doors and windows. John enters, claiming that Dean should be proud of what he does for the family. Dean grows suspicious of the kind words and points the Colt at John. Sam allies himself with Dean, and John is revealed to be possessed by the Demon as his eyes glow yellow. The Demon injures both boys and taunts Sam's unreliable special powers, and he also mentions that Sam was about to propose to Jessica. Dean draws the Demon's attention away from Sam, and it reveals that the demons in Meg and Tom were his children. He uses some psychic power to attack Dean, causing him to bleed internally. Dean begs for his life, and John manages to surface long enough for Sam to free himself and grab the Colt. John begs Sam to kill him in order to kill the Demon while Dean pleads for Sam not to shoot. Sam uses the penultimate bullet in the Colt to shoot John in the leg, forcing the Demon to leave John's body.

Sam drives the Impala with John in the passenger seat and Dean, gravely hurt, in the backseat. John expresses disappointment that Sam didn't shoot and end the family's quest, but Sam says that killing the Demon is not the most important thing. Sam promises to get them to the hospital, but a huge truck slams into the Impala, smashing it and rendering all three Winchesters unconscious. The truck driver has the black eyes of the possessed.