[s4e21] When The Levee Breaks Online

: Directed by Robert Singer and written by Sera Gamble. It is one of only three episodes in the entire series where no characters die.

: Faces internal conflict after being ordered to sabotage the brothers' efforts, ultimately capturing Anna Milton when she confronts him about his actions. Lore and Production Details

: The title is a nod to a 1929 blues song famously covered by Led Zeppelin in 1971. [S4E21] When the Levee Breaks

" When the Levee Breaks " is the 21st episode of Supernatural 's fourth season and the 69th episode overall. Premiering on May 7, 2009, it serves as the penultimate episode of the season, directly setting the stage for the apocalypse.

: During withdrawal, Sam suffers intense hallucinations, seeing himself tortured by the demon Alastair , being accused of betrayal by his 14-year-old self , and receiving misguided encouragement from a vision of his mother, Mary . : Directed by Robert Singer and written by Sera Gamble

: Ruby reveals that Lilith is "Lucifer's first" demon and that only she can break the final 66th seal.

: Dean tracks Sam to a motel, leading to a violent brawl. After Sam nearly strangles him, Dean delivers a final ultimatum: if Sam walks out the door, he should never come back. Sam leaves, effectively severing their bond as they head into the finale. Major Character Dynamics Lore and Production Details : The title is

: Under orders, Castiel surreptitiously releases Sam from the panic room. After a tense standoff where Sam dares Bobby to shoot him, Sam escapes and reunites with Ruby to consume more demon blood.