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.
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.
Lucifer takes Sam on a trip through Sam's memories to convince him to agree to possession. Meanwhile, Castiel goes to determine if Amara is dead, and Dean and Crowley come up with a plan to send Lucifer back to his cage.
When Sam is unable to sleep and won't leave the bunker, Dean suggests that they look into the case of a retiree who bashed his head in while yelling that he could hear someone screaming.
Sam and Dean pay a visit to Jody after one of her wards, Claire Novak, calls them and insists that there are monsters in their town. A corpse soon turns up, and Jody and the Winchesters realize that Claire was right.
When a babysitter is murdered on Valentine's Day and her heart torn out of her chest, the Winchesters learn about it and investigate. They discover that an ancient curse is responsible for the death, and that it's passed on by kissing. To save the next victim, Dean kisses her... marking himself for death.
The Winchesters launch a desperate attempt to recover an artifact capable of destroying Amara by sending Dean back to 1943 to recover the Hand of God from a doomed submarine. They're unaware that Castiel--secretly Lucifer--is the one who must send Dean back through time and return him.
The brothers go to a wake to pay their respects to a dead wrestler who was John's favorite, and discover that the show has left a trail of bodies behind it. Meanwhile, Crowley escapes from Hell and goes to get a weapon capable of stopping Lucifer.
Sam and Dean take a break from looking for Amara to check out a case of a girl going into a coma. They soon discover that their case is connected to a similar case that Bobby and Rufus investigated several years ago... and never completely solved.
Sam and Dean save a couple from two werewolves, but Sam is shot in the process. Dean tries to get Sam and the couple to safety, but Sam dies... and Dean is forced to abandon him.
Sam and Dean try to convince Crowley to turn over the Horn of Joshua before destroying Lucifer--and Castiel--rather than after they use the Horn to defeat Amara. Meanwhile, an unexpected ally helps Amara heal from her injuries, and Lucifer makes the angels in Heaven an offer they can't refuse.
The Winchesters investigate a series of mysterious disappearances every 27 years, and run into a pair of hunters where one is looking for revenge against the creatures that took his brother.
The brothers investigate a murder-suicide in Colorado that may be tied to Amara. Meanwhile, Metatron receives a request to edit a new book.
Sam and Dean try to come up with a way tor rescue Lucifer, and discover Chuck's plan to deal with Amara. Meanwhile, a new Prophet is awakened, but he's less than thrilled at the promotion.
To defeat Amara, Sam and Dean will first have to help Chuck and Lucifer reconcile. Once they do, they then must gather the forces of Heaven, Hell, and Magic to weaken Amara so that Chuck can defeat her. However, everything doesn't go quite according to plan.
It's the end of the world as Chuck's death extinguishes the sun. Desperate, the Winchesters, Castiel, Crowley, and Rowena come up with a plan... but to succeed, one of them will have to die.