Episode
An old man, Daniel Elkins, sits scribbling in his journal, drinking Jack in bar in Manning, Colorado. A group of people enter and catch Elkins’ attention. After leaving the bar in a hurry, Elkins is confronted by the woman leading the group he saw earlier. To defend himself, Elkins attempts to load an old 5 shot Colt however after a struggle, he is murdered.In a diner somewhere in Nebraska Sam and Dean are looking over news stories for a job, when they read about Elkins death. Dean recognizes the name from John's Journal and they head west. Arriving at Elkins' cabin, the boys find it ransacked and in chaos, but in the darkness, they are being watched. Amongst the wreckage Dean finds not only a journal, a lot like their father's, but also a message. A combination to a post office box. A mail drop, just the way their father does it.
Opening the post office box they find a letter addressed to "J.W.". They are startled by the surprise appearance of John Winchester, their father. Reading the letter, he realizes that Elkins had been holding out on him about a legendary gun, a Colt made in 1835. Questioning the boys he realizes that whatever attacked Elkins has taken the gun. He tells them it's Vampires, and they will hunt them together.
As Sam and Dean sleep, John is listening to a police scanner. He hears of an abandoned car left by young couple after making a 911 call. Rousing the boys, they take off to investigate. Sam questions John, but John just asks Sam to follow him. When they reach the location of the abandoned car, 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.
Meanwhile, back at the vampire nest, Kate presents her gifts taken from Elkins, to her mate, Luther. Horrified that she killed the old man, even if it was to avenge his family, he states, “Revenge isn’t worth much if you end up dead”. He then recognizes the gun.
Another confrontation between Sam and John exposes the still seething anger existing between them. However, during their tracking of the Vampire family, John tells them about vampires and they can only be killed by beheading. After a moment, seemingly reluctant, he shares with them the details of what makes the Colt so special and why he needs it.
Working together to attack the 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. John’s plan is to trade her for the Colt. Once again the Winchesters clash over John’s plan to exclude the boys from his final game plan, insisting they leave, to keep them safe. While the Luther and his vampires discover John and Kate and parley for the Colt, Sam and Dean invade the nest, killing the vampire left on watch and 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. They distract Luther and 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.
Info from Superwiki