Swan Song is the 22nd episode and the season finale of Season 5. It aired on May 13th, 2010.
All out of options, Dean Winchester reluctantly agrees on letting Sam be the host for Lucifer so that he can jump into Lucifer's Cage. Remembering what Lucifer said to Dean in the future, they locate him in Detroit. Sam makes Dean promise that if things go as planned, he will make a life for himself with Lisa Braeden. After consuming gallons of demon blood, Sam and Dean allow themselves to be caught by demons and brought to Lucifer. After demonstrating his enhanced powers to kill the demons in the room, Sam consents for Lucifer to possess his body.
It is then that Lucifer reveals that he knows that the Horseman's Rings form the keys to his cage, and that he is wary of the boys' plans to trick him inside. Nevertheless, he agrees to possess Sam and let him try to retain control of his body. After Lucifer enters Sam, he is knocked unconscious, and Dean quickly throws the key to the cage on the wall and opens it with a spell. After waking up Sam, he watches him preparing to enter the pit, but instead Lucifer then reveals that he overpowered Sam in a matter of seconds. He then closes the portal, puts the key into pocket and quickly disappears.
Outside, Dean meets back with Bobby and Castiel, and they observe various natural disasters on television that are occurring around the world. Knowing that Lucifer will try to seek out Michael for their final battle, they call Chuck to get the exact setting for the fight: Noon at Stull Cemetery in Lawrence, Kansas. Elsewhere, Lucifer is reveling in his new vessel while addressing Sam, who is still fighting him from the inside. He tells Sam that he only wants the best for him, and even offers to spare Dean after the world is destroyed. In a show of goodwill, he brings several people from Sam's past - including a former teacher of his and a prom date - and tells Sam that they were all possessed by demons working for Azazel in order to manipulate him. He then offers Sam revenge on them, and then asks him afterwards if he enjoyed it.
Lucifer is seen standing in the cemetery when Michael, who now possesses Adam, arrives. While Lucifer tries to dissuade him from fighting, Michael, although he seriously considers it for a moment, regretfully tells him that he must do so because God wishes it. Before they get underway, Dean, Castiel and Bobby arrive on scene and Castiel throws a Molotov cocktail of Holy Oil on Michael, forcing him to temporarily vanish. Lucifer, outraged at Castiel's action, blows him up with a snap of his fingers, then snaps Bobby's neck after he is shot with a revolver. Dean repeatedly appeals to Sam to overpower Lucifer, who responds by severely beating him until he is barely conscious. However, as he presses Dean against the side of the Impala, ready to deliver another blow, he pauses as he catches sight of a plastic army man in the ashtray of one of the doors.
This triggers memories of Sam's childhood and various warm moments with Dean, which allow Sam to finally overpower Lucifer. He then opens the cage with the Horsemen's rings, when Michael suddenly returns. He says that he won't let it end the way Sam wants it to and charges at him. Sam, now in control, pulls Michael with him into the cage and the portal closes. Castiel then reappears and tells Dean he was resurrected by God and promoted. He then heals Dean and resurrects Bobby.
As they drive home, Castiel mentions that with Michael gone, he intends to take charge of Heaven, likely in anarchy without Michael. Dean tells Castiel that if he runs into God to tell him that he's his next target. Castiel remarks that Dean's angry. Dean complains that he hadn't been properly rewarded by God, reminding that Sam's still stuck in the cage. Castiel reminds Dean that he got what he desired - no Paradise or Hell, "Just more of the same." Castiel then disappears. Dean leaves Bobby and heads for Lisa's house where she gladly welcomes him in. Meanwhile, Chuck, who has been narrating the entire story while writing on his computer, smiles as he brings an end to the story, only to state that "nothing ever really ends, does it?". He then vanishes into thin air with a smile, wearing a white shirt instead of his usual drab clothes.
Outside of Lisa's house, a streetlight outside goes out and Sam is shown standing beneath it, watching Dean through the window.
- Dean Winchester
- Sam Winchester
- Bobby Singer
- Lucifer (possesses Nick and Sam)
- Michael (possesses Adam Milligan)
- Chuck Shurley / God
- Lisa Braeden
- Benjamin Braeden (cameo)
- Meg (flashback; cameo)
Featured Supernatural BeingEdit
- "Rock Of Ages" by Def Leppard
- "Carry On Wayward Son" by Kansas
- This episode has the highest user ratings on IMDb of the entire series. 
- Out of 6,038 votes, the episode received a 9.7 rating.
- Antagonists: Michael and Lucifer.
- This episode marks the final appearance of Michael.
- Bobby dies for the first time onscreen.
- Azazel, John Winchester, Meg, Zachariah and other characters are seen in Sam's flashbacks.
- This episode was intended to be the series finale. However, due to the ratings, Supernatural was renewed for a sixth season.
- Swan song refers to the finale of something, the final act. In this case, it refers to the last episode of the season, and the final fight before the ending of the Apocalypse.
- Lucifer quotes some lyrics to the famous Charlie Daniels song the Devil Went Down to Georgia when he tells Sam "A fiddle of gold against your soul says I'm better than you." The real lyric is: "I'll bet a fiddle of gold against your soul 'cause I think I'm better than you."
- Chuck answering the phone hoping it was "Mistress Magda" might be a reference to Mary Magdalene, a Disciple of Jesus Christ in the New Testament that some believe to be a prostitute or even the wife of Jesus (a theory made famous by the book the Da Vinci Code by Dan Brown).
- Lucifer returns as a Hallucination in Season 7. He later escapes the Cage in season 11 episode "The Devil in the Details".
- When Lucifer is showing Sam all of the people in his life who were really agents of Azazel watching over him, he refers to Sam's prom date Rachel. In "What Is And What Should Never Be", Dean is said to have slept with Sam's prom date Rachel Nave on prom night.
- Dean's line about Sam's hell making his own look like Graceland is a reference to the mansion that Elvis Presley died in.
- Dean's line "I have a bad feeling about this" may be a reference to Star Wars, in which the line is repeated many times. Eric Kripke originally pitched the show as “Star Wars in truck Stop America”. The series is further referenced in this episode when Dean calls Bobby "Yoda" and Lucifer calls Sam "young Skywalker".
- Chuck states that the Impala rolled off the assembly line on April 24th, 1967. April 24th is Eric Kripke's birthday.
- The name of the Impala's first owner is Sal Moriarty, a reference to Sal Paradise and Dean Moriarty, the main characters in the novel On the Road.
- Stull Cemetery is a real cemetery near Lawrence, Kansas, where Sam and Dean were born. It has a lot of real-life lore associated with it, including the belief that it could be a gate to Hell.
- The tape Dean loads into the cassette deck in the Impala as he drives into Stull Cemetery is labeled with Kim Manners' signature line "kick it in the ass!"
- It is a 12-hour drive from Detroit, MI to Lawrence, KS.
(Seeing Castiel snoring in the back seat of the Impala)
- Dean: Aww, ain't he a little angel.
- Sam: Dean, angels don't sleep.
- Castiel: Hey, Assbutt!
- Lucifer: No one dicks with Michael, but me!
- Dean: Your Hell's gonna make mine look like Graceland.
- Dean: Cass, are you God?
- Castiel: That's a nice compliment, but no.