One Year Later, and Dean’s escaped from Purgatory, though Castiel is nowhere to be found. However, Dean isn’t alone. He’s returned with a mysterious comrade-in-arms whose reason for escape is perhaps more than Dean bargained for. Meanwhile, Sam finds himself reconciling the life he discovered while Dean was gone with Dean’s sudden reappearance.

Kevin talks Sam and Dean into checking in on his mother. When they arrive, they see that Crowley has surrounded her with demons so they rescue her and take her along on their quest to find the tablet. However, they soon discover Kevin wasn’t kidding when he said his mother was a strong-willed woman after she tries to take on Crowley.

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 and Dean investigate a bizarre murder in a college town. Close on the tail of their suspect, they bust into an apartment to find two dead bodies and a laptop cued up to some disturbing video footage.

After Benny gets brutally beat up by vampires, he calls Dean for help who abruptly packs up and tells a confused Sam that he’s taking a personal day. Meanwhile, Sam uses his solo time to reflect on the life he left behind with Amelia.

Sam and Dean investigate a murder and find Garth is already on the case. Dean is not happy to learn that Garth has assumed Bobby’s duties, but someone had to pick up the slack.

Sam and Dean are stunned when Castiel suddenly appears back on Earth with no memory of how he escaped from Purgatory. Meanwhile, Mrs. Tran enlists a witch to concoct a demon bomb.

Castiel tells Sam and Dean that he’s decided to become a hunter like them. Sam and Dean aren’t sold on the idea but agree to investigate a case Cas found where a man’s heart literally burst through his chest. The guys discover that all the deaths resemble cartoon deaths.

Sam asks a hunter named Martin to keep an eye on Benny without telling Dean. However, when Martin tells Sam and Dean there was a vampire kill and that Benny is responsible, Dean defends his friend.

After Naomi orders Castiel to rescue an angel being held captive by Crowley, he turns to Dean for help. Meanwhile, Sam meets with Amelia who asks him to make a choice: stay with her or leave and never contact her again.

Sam and Dean investigate the mysterious deaths of two LARPers who were playing a game titled Moondoor. The guys are thrilled to discover that the Queen of Moondoor is none other than Charlie.

Sam and Dean are stunned when a man who claims to be Henry Winchester, their grandfather, suddenly appears in their hotel room demanding to know where he can find John Winchester, their father.

Sam and Dean investigate the death of Rabbi Bass, who appears to have spontaneously combusted. The case becomes even more confusing when they learn that the Rabbi was researching Nazi Necromancers.

Kevin deciphers the demon tablet and figures out how to close the gates of Hell. He tells Sam and Dean that according to the tablet one person must face a series of three trials, and the first one is to kill a hellhound.

A police officer named James, who turned to witchcraft after working a case with Sam and Dean, is plagued by nightmares in which he murders innocent people.

Sam and Dean are stumped when they investigate a possible zombie case where an amnesiac man dies and then revives himself every day. After the man is attacked by the goddess Artemis, Sam and Dean realize he’s not a zombie.

Castiel reappears in Sam and Dean’s life and tells them Crowley has unleashed several demons into a small town in order to find Lucifer’s Crypt, which holds a valuable relicts. While interrogating a demon, the three discover Crowley has been torturing Meg, who knows the location of the crypt.

Sam and Dean investigate some recent vampire kills and are surprised to learn Krissy Chambers is involved. They find Krissy and learn her father was killed and she’s been taken in by a man named Victor, who has taken in a group of orphan kids to teach them how to hunt.

Kevin is terrified. He has started hearing Crowley's voice in his head and calls Sam and Dean for help. After hearing Kevin's news, Sam and Dean team up with a reaper named Ajay, who helps them with the second trial from the demon tablet.

Concerned about the physical toll the second trial took on Sam, Dean benches his brother from hunting until he heals up. So, when geektastic hacker Charlie Bradbury stumbles upon a case, Dean decides it's time to teach Charlie how to be a hunter-in-training.

When Sam and Dean receive a distressing video message from Kevin Tran, they set out trying to uncover the third trial. The boys make a discovery that sends them to a casino in Colorado where they find a mysterious recluse who may be able to fill in the holes in Kevin’s research. Meanwhile, Castiel tries to elude Naomi and the angels hunting him.

Sam and Dean are reunited with Castiel as they are digging through the Men of Letters' files. They stumble upon an film which could be the key to completing the third trial. Metatron enlists Cass to mull over problems at home.

With Crowley poised to undo all the good they’ve ever done as hunters, Sam and Dean find themselves cornered. But with Kevin's help, the Winchesters ready themselves for one last play against the King of Hell. Metatron initiates a plan with Castiel to take on Naomi and the bureaucracy of Heaven.

With Sam's life on the knife-edge, Dean appeals to the fallen angels for help. Unfortunately, most of them only see Dean as a means to get to Castiel and exact vengeance on the one who caused them to Fall.

Dean and Sam take a captive Crowley to the Men of Letters base in the hopes that he will give up the names of the people possessed by his minion demons. But before they can get any information they are called away to investigate the disappearance of three soldiers.

Castiel makes his way to the Winchesters but discovers a band of angels are hunting him, intent on exacting vengeance for what they believe is his role in their fall from Heaven. Meanwhile, Ezekiel continues to repair Sam, but informs Dean that there is a price to be paid.

With the help from Charlie, Sam and Dean inadvertently release two individuals contained inside of the Men of Letters bunker who where both imprisoned in 1935. They soon discover that one of the individuals is Dorothy of Oz, and she is hot on the trail of the Wicked Witch of the West.

To track down a killer, Dean uses a spell which allows him to speak with the only witness, a German Sheppard. However, he soon discovers that everything is going to the dogs when the spell starts making him act like a canine as well.

Castiel is working as a convenience store clerk and learns of a series of local disappearances. He call the Winchesters, but Dean insists on Sam staying with Kevin to research the demon tablet while he help Cass.

Sonny, a man who runs a boy's home, calls Dean for help after a mysterious death. When Sam wonders how his brother knows Sonny, Dean explains that he spent two months at the boy's home when he was 16, after being arrested for theft.

When members of a virgin chastity group are abducted, Sheriff Jody Mills asks Sam and Dean for help. The Winchesters go undercover to track down the missing members, but when Dean disappears, Sam and Jody end up having to track him down.

The angels are embroiled in a bloody civil war, and Castiel is swept up in the conflict. Meanwhile, Dean realizes that Ezekiel is not who he claims to be and tries to warn Sam with dire results.

Dean and Castiel make a deal with Crowley in order to contact Sam's consciousness so he can expel the angel Gadreel from his body. However, Abaddon is hot on their trail and Crowley has plans of his own.

Crowley turns to Dean for help to locate the First Blade, the only weapon that can kill Abaddon. However, the trail leads them to the biblical Cain. Meanwhile, Sam asks Castiel for help when they need to extract the remaining angel grace from Sam's body to track Gadreel.

Six months after his disappearance, Garth turns up injured in a hospital. Sam and Dean arrive separately to investigate and soon discover that their friend has undergone a startling transformation.

Two dead victims show up with all the fat having being stolen from their bodies. Sam and Dean go undercover in order to investigate a local spa, and discover that a monster is preying on the overweight.

While Sam and Dean try to track down Kevin's mother, Castiel is captured by an old battle-comrade and learns more about the factions of angels.

The Winchester brothers investigate a murder that was apparently caused by a ghost. Sam and Dean discover that the Ghostfacers, Ed and Harry, are already on the case.

Sam and Dean are searching for the First Blade and end up having to track down the missing Crowley and discover that he's now thoroughly addicted to human blood. The Winchesters decide that going cold turkey is the only way.

When Dean chooses to stay in the bunker and try and locate Abaddon, Sam goes to a small Illinois town to investigate a string of vicious murders committed by seemingly harmless individuals.

Castiel investigates the mass slaughter of angels and finds a lone survivor and an old friend. Meanwhile, Sam and Dean capture Gadreel, and Metatron begins the ending of his story.

Sheriff Jody Mills befriends a young girl on the run from vampires. When she's forced to kill one of the monsters, Jody calls in Sam and Dean for help. However, they discover that everything isn't at it seems.

Sam and Dean learn about a monster killing in Chicago and head there to investigate. What they find is a young cop whose girlfriend was killed by the same creature, and who is caught between five powerful clans of monsters who jointly control the city.

Abaddon finally gets something that she can use as leverage against Crowley to force him to lure the Winchesters into a trap. Meanwhile, Castiel rallies his forces and asks Sam and Dean to come in and help him interrogate a captive angel with ties to Metatron.

After an angel carries out a suicide attack on an ice cream shop to kill one angel from another faction. Sam and Dean investigate and discover that the target was one of Metatron's angels and that Castiel may be responsible.

After attacking Gadreel, Dean leaves with Crowley to track down Metatron and kill him. Meanwhile, Gadreel takes Castiel into Heaven to try and break Metatron's connection to the angel tablet.