Though Castiel doesn’t kill Bobby, Dean and Sam, he warns them to stay out of his business. When Castiel assumes his new role as God, he sets out to make things right in the world. Dean decides that they need to find death and ask him to stop Castiel. However, later Castiel finds that he cannot control most of the monster souls and wishes to send them back to purgatory with the help of the brothers. The Leviathan throw around Bobby and Dean and then start bleeding, staggering and dying. Dean discovers that if the beasts remain inside Castiel’s body, they will destroy it. The Leviathan disperse in the nearby water supply and possess different people in an attempt to maintain a food supply. The brothers are injured as they try to fight the Leviathan and the ambulance they are riding in is taking them to Sioux Falls General.

Eventually, Bobby springs them from Sioux Falls General, and they decide to lay low for a while. As Sam is collecting food, he discovers that an unknown serial killer has returned, and he takes off on his own to find her. It is later discovered that the serial killer is Amy, who removes the pituitary gland in the brain as nourishment. Eventually, Dean tracks down Sam and decides that they need to kill the serial killer. Sam and Dean also learn that an Egyptian god is responsible for some of the murders that have been taking place. Apparently, the god puts people on trial for past mistakes and kills them if they are found guilty. The god, Osiris finally catches up to the brothers and puts Dean on trial. However, before he can kill Dean, Sam stabs him to death. Meanwhile, the Leviathan still hunts the brothers.