One Year Later 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. As the boys struggle with their unexpected reunion, they make a shocking discovery that could lead them on a deeply personal mission to settle old scores. If only they could agree – is this a “family business” or isn’t it?

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. The footage begins with Brian, Mike and Kate hearing about an unusual animal attack in their town and the rest of the story is revealed through their eyes. Sam and Dean become unknowing participants in a unique student film.

After Benny gets brutally beat up by some vampires, he calls Dean for help. Dean abruptly packs up and tells a confused Sam that he’s taking a "personal day." Benny confesses that he’s going after his Maker so Dean offers to help, flashing back on the many times Benny helped him and Castiel in Purgatory. Meanwhile, Sam uses his solo time to reflect on the life he left behind with Amelia. However, when things go bad for Dean and Benny, Dean calls Sam for help, which makes everything very complicated.

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 Garth points out that both Sam and Dean have been missing for the last year and someone needed to do it. They guys discover an "avenging ghost" is responsible for the murders and they need to find the source before the killings starts again.

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, but the witch double crosses Mrs. Tran and turns her and Kevin over to Crowley.

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 there has been more than one odd murder in the small town and all of them resemble cartoon deaths.

Sam asks a hunter named Martin to keep an eye on Benny without telling Dean. However, when Martin tells Sam there was a vampire kill and he thinks Benny is responsible, Dean defends his friend. When Martin decides to take things into his own hands, things get messy and Dean is forced to make a very hard decision.

Naomi tells Castiel that Crowley is holding an angel captive and Castiel must rescue him before Crowley finds out their secrets. Castiel 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 (Live Action Role Playing) who were playing a game entitled Moondoor. The guys are thrilled to discover the Queen of Moondoor is none other than Charlie. The three learn that a fairy has been commandeered to harm people and the only way to stop her is to find her master.

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. Henry has time-traveled to stop a demon named Abbadon and was looking for John’s help. Through Henry, Sam and Dean learn more about their father and the Winchester blood line.

Sam and Dean investigate the death of Rabbi Bass, who spontaneously combusted. The case becomes ever more confusing when they learn that the Rabbi was researching Nazi Necromancers. Sam and Dean are attacked by a Golem who turns out to belong to the Rabbi’s grandson, Aaron. The key to the case lies with the Golem but Aaron doesn’t know how to control him, which leaves everyone in danger.

Kevin deciphers the 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 tests designed by God. The first one – kill a hellhound. Sam and Dean argue over who should complete the trials.

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. However, when the murders actually happen, Sam and Dean are called in by James’s "familiar" to help -- but the brothers aren’t sure they want to save a witch.

Sam and Dean are stumped when they investigate a possible zombie case where an amnesiac man dies and then revives himself once a day. After the guy is attacked by the goddess Artemis, Sam and Dean realize he’s not a zombie but instead a God, more specifically, Prometheus.

Castiel reappears in Sam and Dean’s life and tells them Crowley has unleashed several demons into a small town. The demons are looking for Lucifer’s Crypt, which holds a valuable asset, but Castiel lies to Sam and Dean about what it is. While interrogating a demon, the three discover Crowley has been torturing Meg, who knows the exact location of the crypt. Sam and Meg fight to hold Crowley off while Dean and Castiel go in search 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. Victor is helping the teenagers find the vampires who took their parents so they can get revenge. Sam is intrigued by Victor’s method of giving the teenagers a home life as well as a hunting life, but Dean is suspicious of Victor’s motives.

Sam and Dean respond to a call from Kevin, who is terrified after hearing Crowley's voice in his head. After hearing Kevin's news, Sam and Dean team up with a reaper named Ajay, who helps them deal with the second trial from the Tablet. Meanwhile, Dean receives a visit from Naomi and realizes he must find Benny and ask for a huge favor.

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 stumbles upon a case and finds the boys, Dean decides it's time to teach Charlie how to be a hunter-in-training. While happy to see "her highness," the boys suspect Charlie is hiding something; a secret that could get her killed.

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

Sam and Dean reunite with Castiel. Digging through the Men of Letters' files, they stumble upon an undiscovered film which could be the key to the third trial. Metatron enlists Cass to mull over problems at home. Meanwhile, Crowley digs into Sam and Dean's past.

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 Winchester brothers bound into one last play against The Demon King. Metatron initiates a plan with Castiel to take on Naomi and the bureaucracy of Heaven.

While Sam hangs on the edge of life and death, Dean appeals to the fallen angels for help. Unfortunately, most of them only see Dean as a means to get to Castiel and exact bloody vengeance on the one who caused them to Fall. Meanwhile, Sam wrestles with his inner demons and Castiel learns what it means to be human.

Dean and Sam take a captive Crowley to the Men of Letters base in the hopes that he will give up the names and host bodies of his minion demons. However, they are called away to investigate the disappearance of three soldiers, which leads them to Abaddon, the Knight of Hell... and forces Ezekiel to take control of Sam's body to save his life.

Castiel makes his way to the Winchesters but discovers a band of angels are hunting him, intent on making him pay for what they believe is his role in banishing them from Heaven. Meanwhile, Ezekiel continues to repair Sam's price, but informs Dean that there is a cost to be paid.

With some help from Charlie, Sam and Dean inadvertently release two individuals contained inside of the Men of Letters bunker: an evil witch, and a young woman, both imprisoned since 1935. They soon discover that the woman is Dorothy of Oz, and she is hot on the trail of the Wicked Witch, who plans to summon her evil army to Earth and conquer the planet.

To track down a killer, Dean uses a spell to talk to a German Sheppard that was at both murders. 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 Tablet while he investigates.

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

When a mysterious abductor targets members of a virgin chastity group, Sam and Dean go undercover to track down the killer when Sheriff Jody Mills asks them for help. However, Dean disappears and Sam and Jody end up tracking him down.

The angels fight each other in 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 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, they soon discover that the trail leads to Cain... the Father of Murder and the most powerful demon of all time. Meanwhile, Sam asks Castiel for help when they need to extract the remaining 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... and found others who share his condition.

Two victims die and the fat is stolen from their bodies. Dean and Sam investigate a local spa and go undercover, 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 brothers investigate a mysterious murder that was apparently caused by a ghost, and discovers that the Ghostfacers, Ed and Harry, are already on the case. However, the facts don't add up and the Winchesters realize that something more is going on.

Sam and Dean track down the missing Crowley and discover that he's now thoroughly addicted to human blood. Once they get him sober, the brothers go seeking the First Blade and find it in the possession of a former Man of Letters... who plans to add Dean to his collection.

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. He's unaware that Dean has actually gone out drinking to deal with the strain of unleashing the Mark of Cain.

Castriel 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 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 when the girl wants to go back to the vampires.

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. However, war is about to break out and the sides are drawn as the Winchesters discover that the original victim belonged to one of the clans.

Abaddon finally gets something that she can use as leverage against Crowley to force him to lure the Winchesters. 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 a suicide angel takes out an ice cream shop to kill one enemy angel, Sam and Dean investigate and discover that the target was one of Metatron's angels... and that Castiel may be responsible. Meanwhile, Metatron tries to consolidate his hold over the angel factions with promises that he will restore them to Heaven.

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, stripping him of his powers.