The third season of Supernatural, an American dark fantasy television series created by Eric Kripke, premiered on October 4, 2007, and concluded on May 15, 2008. Traveling throughout America, protagonists Sam and Dean Winchester use their father's journal to help them carry on the family business—saving people and hunting supernatural creatures. The season begins with the brothers tracking down the demons released from Hell in the previous season finale. They become allies with a demon named Ruby, who claims to know a way to release Dean from his demonic pact—he had sold his soul to a demon and was given a year to live in exchange for Sam's resurrection—and wants to protect them from the new demonic leader Lilith. As Dean's deadline approaches, their efforts are further hindered by Bela Talbot, a professional thief of occult items who is often at odds with the Winchesters.

"All Hell Breaks Loose" is the joint title for the two-part second-season finale of The CW television series Supernatural. It consists of the twenty-first and twenty-second episodes of the second season. "Part One" was first broadcast on May 10, 2007, and the second part aired the following week on May 17, 2007. The narrative follows series protagonist Sam Winchester —a young man who travels the continental United States with his brother Dean hunting supernatural creatures—as he is abducted by series villain Azazel and sent to an abandoned town. Azazel intends to find a leader for his demon army by having Sam and other psychic children like him fight to the death. Sam is eventually killed, but is resurrected after Dean sells his soul. The sole survivor, Jake Talley, is sent by Azazel to a cemetery protected against demons, where he opens a gateway to Hell. At the end of the episode, Azazel is finally killed by Dean with the mystical Colt revolver, but not before hundreds of demons are released into the world.