After Bobby discovers Crowley has no intentions of returning Bobby's soul, the hunter takes matters into his own hands. He calls on Sam and Dean for help after he unearths one of Crowley's deepest secrets. Meanwhile, Sam and Dean learn what Bobby does all day when they are not around.

Dean is furious after Sam disappears to follow a lead on a case with clues that are identical to a case Sam solved as a kid. The demon turns out to be Amy, who has been killing low-life thugs and taking their brains for dinner - the same demon Sam found as a kid.

Sam and Dean investigate a string of unusual murders where the victims were all recipients of organs from the same donor. The killer is captured, but things become even more complicated when the brothers find their killer in a trance mumbling an ancient prayer.

Sam continues to try to save Dean from the Mark of Cain. Realizing that Dean's antics are causing problems for him in hell, Crowley seeks help from a reluctant Castiel.

While Rowena tries to consolidate her power to protect herself from the Winchesters, Sam and Dean search for a missing baby connected to the Darkness. Meanwhile, Castiel struggles to heal and Crowley tries to find a way to use the Darkness for his own personal gain.

Sam and Dean investigate the mysterious death of a girl and the disappearance of another.