Season synopsis
Contains spoilers for this season and earlier seasons.
A year after Sam sacrifices himself to stop Lucifer, Dean is trying to live with Lisa and her son Ben when Sam reappears and pulls him back into hunting. Sam has spent months working with their maternal relatives, the Campbell hunters, and their resurrected grandfather Samuel. Dean learns that Samuel and Bobby knew Sam was back while Dean grieved. The family hunts Eve, the Mother of All, whose hybrids threaten to spread through human communities.
Eve reveals that Crowley is alive and hunting Purgatory's souls, exposing the stakes behind Castiel’s secret deal with the King of Hell. Dean kills Eve after she bites him, using phoenix ash he has swallowed to poison her. Sam returned from the Cage without his soul, making him ruthless and emotionally detached. Death restores it but places the Cage memories behind a mental wall. When Castiel breaks that wall, Sam becomes comatose while Dean and Bobby try to stop the angel's plan.
Castiel and Crowley have been trying to open Purgatory so they can use its souls in the war against Raphael. Castiel changes the ritual by switching the blood, leaving Crowley with nothing while he absorbs the souls himself. He then destroys Raphael and tells Dean and Bobby that he is the new God. Dean asks him to return the souls and give up the power, but Castiel refuses, saying he has Raphael's followers to deal with. The season ends with Castiel claiming authority over Heaven and Earth.