After the Darkness passes over them, Sam and Dean wake up and Dean realizes that he encountered the creature at the heart of the storm. Meanwhile, Castiel prays to Heaven to help him, and Crowley takes steps to avoid Castiel.
While Sam tries to find a cure for the Darkness virus invading his body, Dean takes Jenna to her grandmother's. Meanwhile, the angels torture Castiel for Metatron's information, and Crowley learns of the Darkness.
When the Winchesters learn of demons killing witches, they approach one and have her find them Rowena so that they can have her cure Castiel. Meanwhile, Crowley raises the young Amara in Hell but soon discovers that the Darkness may be beyond his control.
Sam and Dean battle a part-vampire/part-ghoul creature that is trying to raise an army to fight the coming Darkness. Meanwhile, Sam receives another cryptic vision, and the Impala witnesses everything.
Sam and Dean track down a double axe-murder at Lizzie Borden's home, and soon realize that something Supernatural is involved. As they continue their investigation, they soon discover that Amara is responsible for creating an army of soulless killers.
Songs: Harry Dacre
-- Daisy Bell (Bicycle Built for Two)
Sam and Dean get a lead on Amara's location, and try to break in to Crowley's stronghold to kill the embodiment of the Darkness. Meanwhile, Castiel tracks down Metatron and finds him in sorry straits.
A college student wearing a rabbit mask kills a man in Minnesota, and Sheriff Donna calls in Sam and Dean for help. They soon deal with the rabbit, but a harlequin and then a clown attack the local high school coach. Meanwhile, Dean finds Sam praying to God.
Sam's imaginary friend Sully appears at the bunker and asks the Winchesters for help. Someone is murdering his fellow imaginary friends, and he needs hunters to track the killer down.
While Sam enters Hell with Crowley and Rowena to confront Lucifer and seek his help defeating Amara, Dean investigates the scene of Amara's recent killing and discovers that she has plans for him.
Dean and Crowley join forces to find a way to send Lucifer back to his prison. Meanwhile, Lucifer tries to convince Sam to let him take over willingly.
Sam and Dean investigate two mysterious deaths at a retirement home. Each victim was uniquely vulnerable in some way, and each one bashed his head open while claiming to hear an unearthly screaming.
Claire Novak, now living with Jody, suspects that there are monsters in their quiet town and calls in the Winchesters. A beloved teacher soon turns up dead, confirming Claire's suspicions. However, Jody is more interested in getting Claire back into college and helping her get along with Alex, who she's also taken in.