Sam and Dean investigate a double-murder at the B&B built in axe murderer Lizzie Borden's house, and discover what Amara has been doing since the last time they saw her.
The Winchesters decide to take a road trip to get out of the bunker, but find themselves in a life-or-death struggle with creatures intent on raising an army to fight the Darkness.
While Crowley tries to bend Amara to his will, Sam and Dean track down Rowena so that she can undo the attack dog spell that she cast on Castiel... before it kills him.moreless
While Dean delivers Jenna and Amara to Jenna's grandmother, Sam tries to find a cure to the Rabid plague in Superior. Meanwhile, Hannah rescues Castiel from the other angels, and Crowley learns of the Darkness child.moreless
After the Darkness passes them by, Dean begins to remember his encounter with the intelligence at the heart of their new foe. Meanwhile, the Darkness spreads, turning men into killers. Crowley escapes Castiel and makes plans to return to Hell, while Castiel beseeches his fellow angels to help him.moreless
Sam has Castiel convince Crowley to find the three ingredients for the spell necessary to cure Dean of the Mark. Meanwhile, Dean continues to sink deeper under the Mark's influence, and contacts a former ally for help.moreless
While Dean hunts down Charlie's killers, Sam has no choice but to fulfill his end of his bargain with Rowena.
Sam and Dean investigate a woman whose eyes were removed and run into the mysterious Styne family again. Meanwhile, Sam goes behind Dean's back to recruit Charlie and Castiel to help Rowena decipher the Book of the Damned. In Hell, Crowley talks to Olivette and finds a bargaining chip that he can use against his mother.moreless
Claire tries to find her mother Amelia, and Castiel ends up trying to help her... and asks Sam and Dean for help.
To help Rowena translate the Book of the Damned, Sam looks for a Codex. However, the Codex is sealed in a magical Werther Box created by Cuthbert Sinclair, and kills anyone who tries to open it.moreless
Charlie calls Sam and Dean and tells them she found the Book of the Dead that could help remove the Mark of Cain. Unfortunately, a man who claims the book belongs to his family shoots her. Meanwhile, Castiel and Metatron take a road trip to find Castiel's grace, but the journey doesn't go as planned.moreless
While Sam and Castiel free Metatron from Hell, Dean goes out drinking and meets Rowena. Meanwhile, Crowley decides what to about his mother.
The Winchesters investigate a series of deaths involving disembowelment. In each case, the victims attended the same church and confessed to the same priest. Meanwhile, Crowley captures Olivette and turns her over to Rowena in the hopes that she'll stop taking out her frustrations on his royal court.moreless
The brothers investigate a soldier's brutal death and discover that another soldier was responsible. The trail leads to a third soldier who has developed an incredible thirst... and is a friend of Cole's.moreless
While Crowley tries to deal with his mother, Sam and Dean confront Cain over the Mark.
Sam and Dean try to stop a ghost who is taking revenge against a group of college students by killing people through various electronic devices.
Dean gets a rude awakening when he encounters the fairy tale Hansel, who is trying to keep the evil witch from killing him. Unfortunately, Hansel sacrifices his victims' age... and reduces Dean to a teenager.moreless
The Winchesters are surprised to see a video on the Internet of Charlie torturing a district attorney. Sam and Dean go after her, and discover that she's after the man responsible for the car crash that orphaned her. However, the Charlie they find isn't the Charlie that they expect.moreless
Sam and Castiel turn to Metatron for help trying to cure Dean, while Claire plans revenge against the man who killed her second father. Meanwhile, Rowena continues her plan against her son Crowley.moreless
Castiel turns to Sam and Dean for help, when he tries to help the daughter of the man he's possessing but she escapes. Meanwhile, Crowley and Rowena have a chat, and Dean worries about what will happen if he gives in to the Mark again.moreless
During a sheriff's retreat, Jody stumbles across murders involving eaten corpses and calls in Sam and Dean. When they arrive, they ask Jody to keep overeager Sheriff Donna Hanscum distracted while they look into the killings.moreless
Sam and Dean track down a demon prostitution ring which leads them to the witch Rowena. They go after her, unaware that Cole is still on Dean's trail. Meanwhile, the husband of Hannah's host body comes looking for his wife, complicating things for Hannah and Castiel.moreless
Dean learns that Bobby is the beneficiary in an heiress' will. With no monster sighting, the Winchesters go to find out what Bobby received. However, what they find is a murder and a possible husband-and-wife team of killer ghosts... or so they believe.moreless
Sam and Dean investigate the disappearance of a teacher at an all-girls school and discover that the students are putting on a musical based on Chuck Shurley's Supernatural novels based on their lives.moreless
Dean insists on going hunting on what he figures is an easy case: three werewolf-related murders. However, the brothers soon encounter a prior acquaintance and find out that the murders aren't as clear-cut as they seemed.moreless
Sam tries to cure Dean and remove his demonic essence, but discovers that his brother doesn't want to be cured. Meanwhile, Crowley realizes that he will need someone to rally the forces of Hell behind to maintain their loyalty, and seeks out a dying Castiel.moreless
Crowley discovers that Dean is becoming increasingly difficult to control, and contacts Sam to make a deal. Meanwhile, Sam escapes from Cole and returns to his hunt for his brother, and Hannah tries to make a deal with Metatron to save Castiel's life.moreless
Dean embraces his new life as a demon and hits the bars with Crowley. Meanwhile, Sam tries to track down his brother, unwilling to accept what Dean has become, and runs afoul of a man trying to get revenge on Dean for a past crime.moreless
Dean falls increasingly under the spell of the First Blade. Meanwhile, Metatron makes his move against humanity, as Sam, Castiel, and Gadreel try to stop him.
Castiel calls on the Winchesters to help when his army of angel followers are attacked, and Dean is all too eager to help under the First Blade's influence.