On a hunch from Sam, he, Dean, and Bobby find the Campbell family library hidden under Samuel's study. They search Samuel's books for a way to defeat Eve, and Bobby eventually finds a mention of a "Mother" that can be burned by phoenix ashes. Never having heard of a real phoenix, they continue to search until Dean finds Samuel Colt's journal. There is an entry under March 5, 1861, in which Samuel Colt mentions shooting a phoenix in Sunrise, Wyoming, leaving a pile of smoldering ash. Dean is convinced that they need to go back in time to 1861 and gather the ashes so that they can defeat Eve.

Dean prays to Castiel, but another Angel shows up instead. She introduces herself as Rachel, Castiel's lieutenant, and she shows disdain for Sam and Dean. After a few moments, Castiel appears and dismisses her. They explain their plan to Castiel, and he agrees to send Dean and Sam back to March 4, 1861. He can only allow them 24 hours, though, or they will be trapped in the past.

Once they appear in Sunrise, Wyoming, Sam sets the timer on his watch for 24 hours. They walk into town and see a man, Elias Finch, about to be hanged in the town square. A judge reads him his sentence - apparently, Elias killed his wife - and then he's put to death. Sam and Dean are disturbed, but they follow the town's sheriff as he leaves the square and heads to the prison. There, they pose as law enforcement officers and question him about Samuel Colt, but he hasn't heard of him. He sends them to the saloon to question the bartender, an old man who apparently knows everything.

At the saloon, Dean starts to see that life in the Old West is less romantic than he thought: it's dirty, the whiskey is terrible, and the saloon girls are less than healthy. The bartender tells them that Samuel Colt passed through town about 4 years ago but hasn't been back since. Rumours are that he's building a railroad stop about 20 miles away in the middle of nowhere, and Sam and Dean surmise that he's currently working on the giant devil's trap that surrounds the devil's gate in southern Wyoming.

As they're talking, a sex worker named Darla approaches and tries to seduce Dean, but the judge who read Elias his sentence shows up and takes her upstairs. Moments later, they hear her scream, and they rush up to find that the judge dead, burned to ashes. Darla swears that it was Elias' ghost that killed him. That night, Sam and Dean discuss the possibility that the Phoenix isn't a bird at all, but the man, Elias, who wants revenge on the three men that killed him: the judge, the sheriff, and the sheriff's deputy. They decide to split up, Dean staying behind to join the sheriff's posse and hunt down Elias, and Sam going to find Samuel Colt.

Meanwhile, in the present time, Rachel confronts Castiel about what he's doing in order to beat Raphael. According to her, it's unacceptable what Castiel has become, and she pulls out an angel killing sword. She manages to pierce his flesh, but not kill him, and he pulls out his own sword and defeats her. Wounded, he travels to Bobby's house, puts a ward against angels on the wall with his blood, and collapses.

In town the next morning, Dean shows up at the saloon, ready to form up a posse and go after Elias. Nobody shows up to join him, however, and soon the burned body of the sheriff is found. The bartender takes the star from the sheriff's body and pins it on Dean, congratulating him on his new position. After his promotion, Dean goes to find the sheriff's deputy. The man is packing a suitcase, determined to escape "Elias' ghost," but Dean tells him that he won't be able to run forever and that he needs to play his part: as bait.

Meanwhile, Sam finds Samuel Colt's cabin. Samuel has just used Colt to kill two demons that wanted him to open the devil's gate, and he immediately splashes holy water on Sam to make sure that he isn't a demon, as well. Sam tells him that he's a hunter from the year 2011, and that he needs Samuel's help. Samuel is sceptical, so Sam hands him his cell phone, a Blackberry, and Samuel is immediately convinced. Sam then tells him that, according to the copy of Samuel's journal he's carrying, Samuel kills a phoenix in three hours, and Sam needs the ashes to kill a monster he's hunting. Samuel tells him that he's no longer hunting and that he lost the gun gambling, but Sam knows that he's lying, and confronts him. Samuel eventually admits to having the gun, but tells him that no matter what his journal says, he's not going to be killing a phoenix. Sam realizes that he's going to have to kill the phoenix himself, and demands the gun.

In the present time, Castiel tells Bobby the truth: that, given his injury, he won't be able to retrieve Sam and Dean from the past. The only way he can get enough power to save them is to touch Bobby's soul; the risk is that he'll cause Bobby to explode.

Back in 1861, Dean locks the deputy in a cell and, when Elias shows up, he demands that Dean open the cell. Dean refuses and then tosses an iron nail at him. When Elias reflexively catches it, his hand burns, and Dean confronts him with the truth: as a monster, Elias is vulnerable to iron, which is why he couldn't escape his iron shackles before he was hung, and why now he can't open the cell that the deputy is in.

Elias realizes that Dean is a hunter, and so, in an attempt to win him over, tells him why he was put to death. Although a phoenix, Elias was married to a human woman that he loved. On a visit to town, she was assaulted by the deputy, and, when Elias came across them, the deputy shot both him and his wife. Elias' wife died in his arms, but Elias was unable to die, so the deputy, sheriff, and judge pinned his wife's murder on him and tried to put him to death. Dean is moved by his story, but still resolved to kill him, so Elias grabs a gun from a nearby holster and shoots the deputy through his cell bars. Dean jumps out a window to escape Elias' gunfire and is on the run when Sam appears with the Colt in hand.

In the future, Bobby puts a belt between his teeth and Castiel prepares to touch his soul...

Sam gives the Colt to Dean, and he goes into the town square and calls for Elias. It's a duel at high noon, and both men stand ready before drawing their weapons lightning-fast. Elias misses, but Dean hits him with a bullet from the Colt, killing him. They're almost at the 24-hour mark, as Sam reminds him, and Dean rushes forward to gather Elias' ashes when Castiel suddenly pulls them back to the future. Back in Bobby's house, Dean stares at the empty bottle in his hand, stunned.

Bobby and Castiel are still recovering when the doorbell rings. Sam answers it to find a young man from a courier service. He has a package for "Sam Winchester." The young man is curious about the package because it's been around "forever" and was supposed to be delivered to Sam at this house specifically on this date. When Sam hears that the package is from Samuel Colt, he takes it and closes the door in the courier's face without signing for it. Back in Bobby's study, he opens the package while Dean, Castiel, and Bobby look on. First, he finds his cell phone - the Blackberry is dirty and cracked - and then he finds a note from Samuel Colt. In it, he tells him that he found Sam's address and the current date from his "thingamajig", and that he thinks he'll find the "enclosed" useful. Sam digs through the packaging and pulls out a glass bottle full of ashes: Samuel Colt gathered the phoenix's ashes and delivered them to Sam from 150 years in the past.

Information from Supernatural Wiki