Sin City is the 4th episode of Season 3. It premiered on October 25th, 2007.
While Dean helps Bobby work on the Colt, Sam finds some demonic omens and two unusual deaths in Elizabethville, Ohio. The brothers investigate, posing as insurance agents as they speak to Father Gil, who witnessed one of the deaths – a suicide in his church. They find the town, formerly a "half-dead factory town in the Rust Belt," full of lusty people who like partying and gambling.
As they check into a hotel, they run into Richie, a hunter Dean has worked with before. Dean reminds Richie of his previous warning: he's not really cut out for hunting and is going to get himself killed. Richie dismisses the warning. On a tip from him, the boys go to check out a bar owned by Trotter, a local businessman. They are surprised to find Father Gil bellied up to the bar. Suddenly one man shoots another, because he slept with his wife. The man then starts to commit suicide, but Dean tackles him before he can get the shot off. Sam then splashes him with holy water and finds that he is not possessed. After the kerfuffle dies down, they discover Richie has disappeared. Casey, a bartender at Trotter’s, has taken Richie to the basement in a home owned by her parents, where she kills him. She is possessed.
Meanwhile, Bobby is testing the Colt when Ruby arrives, and offers to help him make it capable of killing demons again.
While Dean searches for Richie, Sam investigates Trotter, breaking into his office. He splashes Trotter with holy water, but he appears to be just a human, and Sam leaves to find Dean. Dean has gone with Casey to her basement. He discovered that she killed Richie and has hidden a Devil's trap under a rug, which traps her. Dean tries to exorcise the demon from her, but she destroys the exorcism book, and then traps him in the basement with her by causing a cave-in at the entrance.
She reveals to him that she only encouraged Trotter to introduce things like gambling and prostitution - the behavior in Elizabethville is mainly due to humans’ natural instincts. She also tells him that the Yellow-eyed Demon was actually Azazel. Since his death, the demon hordes that escaped the Devil's Gate in Wyoming are in chaos, since Sam did not take on the role Azazel had planned for him: to lead the demon army. She tells Dean that demons believe in a higher power – Lucifer. Dean and Casey continue to talk, and she develops some respect for Dean.
Sam finds out where Casey lives, and searches the house without finding Dean, but there are traces of sulfur, indicating a demonic presence. He calls Bobby to tell him about this, before returning to Trotter’s bar, where he enlists the help of Father Gil to find Casey and Dean, not realizing that the priest is also possessed by a demon.
When Sam and Father Gil arrive, Dean tries to warn Sam about him. Bobby arrives, but Father Gil attacks him and then Sam. Father Gil breaks into the basement and releases Casey, revealing they have been lovers for centuries. He is about to kill Dean, despite Casey’s protestations, when Sam arrives and kills him with the Colt. As he turns the gun on Casey, Dean calls to him to wait, but he shoots her anyway. Dean stares at Sam as though he doesn't recognize him.
Afterward, the town hasn’t changed much. Dean confesses to Bobby the question that Azazel asked him after Sam coldly dispatched Jake at the Devil's Gate: is he certain that the Sam he brought back is "100% pure Sam?" Bobby rejects his concerns, but Dean is obviously worried.
As Sam prepares to leave, Ruby appears and congratulates him on killing the demons. Sam reminds her that he killed two people in the process, and this upsets him. When he threatens her with the Colt, she again reminds him she can help with Dean’s deal.
Run Through The Jungle by Creedence Clearwater Revival
Bad Seed by Brimstone Hotel
Nikki by Sasquatch
Did You See It by Mother Superior
- Ruby helps Bobby restore the Colt's ability to kill almost anything.
- Lucifer is mentioned for the first time. It is revealed that some demons worship Lucifer as their higher power, and the reason for Lucifer's banishment from Heaven is introduced. Casey says that no demon has actually seen Lucifer, but that they believe that he made them and that he will one day return. At the end of Lucifer Rising, Lucifer does indeed escape his prison and returns to Earth due to the efforts of Azazel, Lilith, and Ruby. It is also confirmed in When the Levee Breaks that Lucifer is responsible for creating the demon race.
- The reveal in Malleus Maleficarum that demons are created from tortured human souls is briefly foreshadowed in an exchange between Dean and Casey. When Dean asks if Dick Cheney is a demon, Casey replies, "Not yet. Let's just say he's got a parking spot reserved for him downstairs." Casey is thus implying that, although Cheney is human now, he will become a demon later on when he goes to Hell.
- Azazel's real name is revealed; previously, he had only been known by nicknames such as "Yellow Eyes."
- Casey reveals that things were meant to go differently, but that Dean ruined the plan by killing Azazel and that Sam's refusal to take over as leader of the demonic army has made the situation worse. Now, many demons are fighting for control and most of them aim to kill Sam as their perceived competition. It had been revealed in All Hell Breaks Loose - Part 1 and All Hell Breaks Loose - Part 2 that Azazel planned on one of his Special Children (he had favored Sam in particular for this position) becoming leader of his army of demons. However, he implies in In The Beginning that this was not the full extent of his plans, which are revealed in Lucifer Rising.
- After witnessing Sam kill Father Gil and Casey without hesitation, Dean confides in Bobby his worries that something has been wrong with Sam since his resurrection. Azazel first suggested this to Dean in "All Hell Breaks Loose - Part 2".
- Sam questions Ruby's reason for wanting to help him, but she refuses to reveal her motives. Although she claims in Malleus Maleficarum that she is different from other demons because she remembers how it feels to be human and so wants to help humans against demons, it is revealed in Lucifer Rising that she is actually manipulating Sam in attempt to free Lucifer.
- Don S. Davis is the second actor from the show Stargate SG-1 to guest star on the show, the first being Teryl Rothery, as a doctor in the episode Heart (and later, Olivette in Season 10), third being Michael Shanks as Rob in the episode 99 Problems and the fourth being Amanda Tapping as the angel Naomi.
- Dean: You have a god?
- Casey: Sure. His name's Lucifer.
- Dean: You mean the Devil?
- Casey: Your word, not ours. Lucifer actually means "light-bringer." Look it up. Once he was the most beautiful of all God's angels. But God demanded that he bow down before Man, and when he refused, God banished him. Tell me, Dean, how do you like bowing before lesser creatures?
- Dean: Lucifer's really real?
- Casey: Well, no one's actually seen him, but they say that he made us into what we are, and they say that he'll return.
- Dean: Oh, yeah? And, uh, you believe that?
- Casey: I've got faith. So, you see? Is my kind really all that different than yours?
- Dean: Well, except that, uh, demons are evil.
- Casey: And humans are such a lovable bunch. Dick Cheney.
- Dean: He one of yours?
- Casey: Not yet. Let's just say he's got a parking spot reserved for him downstairs.
- Dean: So, the gate opened. The demon army was let out. What now, huh? I'm not seeing a big, honking plan here.
- Casey: Honestly, there was a plan. Azazel was a tyrant, but he held us all together.
- Dean: "Azazel"?
- Casey: You think his friends just called him “Yellow Eyes”? He had a name. After you did him in, it all fell apart.
- Dean: Sorry about that.