The Cage was the Winchester's best weapon at stopping the Apocalypse.
After [[Lucifer]] was banished from [[Heaven]] for defying [[God]], he twisted a human [[soul]] into the [[Lilith|first demon]]. After this, God sent [[Michael]] to imprison Lucifer in the Cage which was locked with 600 mystical seals.
In 1972, [[Azazel]] possessed a [[Father Lehne|priest]] at [[St. Mary's Convent]], and killed eight nuns in the chapel. This enabled him to speak to the imprisoned Lucifer. Lucifer tells Azazel that Lilith is needed to break [[the 66 Seals]] that hold him captive in the Cage and that he needs to find a very "special child."<ref name="four22">[[4.22 Lucifer Rising]]</ref> This leads Azazel to recruit [[:Category:Special Children|select children]], including [[Sam Winchester]] and to set in motion events that subsequently lead to the breaking of the 66 Seals.
After the averted Apocalypse, [[Raphael]] tried to reopen the Cage to release Lucifer and Michael, to continue where the angel's plans lefy off, but was ultimately unsuccessful due to Castiel leading a civil war in Heaven to stop him. During this time, Sam is subsequently rescued from the Cage by Castiel, but his soul remained trapped in the Cage being tortured by Lucifer and Michael. [[Death]] agrees to retrieve Sam's soul, and returns it to his body, setting up a temporary "wall" in Sam's mind to prevent the knowledge of the horrors that happened in the Cage from destroying him.
Following the release of [[the Darkness]], cries are heard coming from the Cage, and the demons speculate that Michael or Lucifer are trying to warn them about it. Sam also starts having flashbacks or visions of his torment in the Cage. When Sam finally journey's to Hell to confront Lucifer with [[Crowley]] and [[Rowena]], he learns that the impact of the Darkness' release had a massive effect on Hell, causing the Cage to become damaged. It was through those fissures Lucifer was able reach out and give Sam his visions of the Cage. Lucifer is eventually able to escape in [[11.10 The Devil in the Details]] by taking [[Castiel]] as his [[vessel]].