With Crowley poised to undo everything they've ever done, Sam and Dean find themselves cornered. But with Kevin's help, the Winchesters have one last play against The King of Hell.
As the Third Trial nears, Sam and Dean reunite with Castiel and stumble upon a key to the trial in the Men of Letters files. Crowley digs up some familiar faces from the past.
When Sam and Dean receive a video message from Kevin, they set out to uncover the Third Trial. Meanwhile, Castiel's on the run from Naomi and her angels.
With Sam resting up after the second trial, Dean teams up with adorable hacker/LARPer Charlie Bradbury and teaches her how to be a hunter-in-training.
Sam and Dean respond to a call from Kevin, who is terrified because he's hearing Crowley's voice in his head. After hearing Kevin's news, Sam and Dean team up with reaper named Ajay (guest star ASSAF COHEN), who helps them deal with the second trial from the Tablet. Meanwhile, Dean receives a visit from the angel Naomi and realizes he must find his Purgatory friend Benny and ask for a huge favor.
Sam and Dean investigate some recent vampire kills and are surprised to learn that teenage hunter (and fan favorite) Krissy Chambers (guest star MADISON McLAUGHLIN) is involved. They find Krissy and learn her father was killed and that she's been taken in by a man named Victor (guest star ADRIAN HOUGH) – 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. While Sam is intrigued by Victor's method of giving the teenagers a home life as well as a hunting life, Dean is suspicious of Victor's motives.
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 (guest star RACHEL MINER), 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 are stumped when they investigate a possible zombie case where an amnesiac man (guest star JOHN REARDON) dies and thenrevives himself once a day. After the guy is attacked by the goddess Artemis (guest star ANNA VAN HOOFT), Sam and Dean realize he'snot a zombie but instead a titan – more specifically, Prometheus.
Dean really doesn't like witches! A police officer (guest star CHRISTIAN CAMPBELL), who turned to witchcraft after working a casewith Sam and Dean, is plagued by nightmares in which he murders innocent people. However, when the murders actually happen, Sam andDean are called in by the witch's "familiar" (guest star MISHAEL MORGAN) to help – but the brothers aren't sure they want to save awitch.
Kevin finally deciphers the God tablet and figures out how to close the gates of Hell. He tells Sam and Dean that, according to thetablet, one person must face a series of three tests designed by God. The first one – kill a hellhound! Sam and Dean argue overwho should complete the trials.
Sam and Dean investigate the death of a Rabbi (guest star HAL LINDEN), who spontaneously combusted. The case becomes ever moreconfusing when they learn that the Rabbi was researching Nazi Necromancers. The Winchesters are attacked by a Golem (guest starJOHN DeSANTIS) who turns out to belong to the Rabbi's grandson, Aaron (guest star ADAM ROSE). The key to the case lies with theGolem…but Aaron doesn't know how to control him – leaving everyone in danger.
Sam and Dean are stunned when a man who claims to be their grandfather, Henry Winchester (guest star GIL McKINNEY), suddenly appearsin their hotel room demanding to know where he can find John Winchester. Henry has time-traveled to stop a demon named Abbadon(guest star ALAINA HUFFMAN) and was looking for John's help. Through Henry, Sam and Dean learn more about their father and theWinchester blood line.
FELICIA DAY returns! Sam and Dean investigate the mysterious deaths of two LARPers (Live Action Role Players) who were engaged in a game entitled Moondoor. The guys are thrilled to discover the Queen of Moondoor is none other than Charlie Bradbury (guest star FELICIA DAY), their quirky hacker friend who helped them fight Dick Roman last season. The three learn that an actual fairy (guest star TIFFANY DUPONT) has been enslaved and commandeered to harm people – and the only way to stop her is to find her master, an overzealous participant in the game.
Naomi (guest star AMANDA TAPPING) tells Castiel that Crowley is holding an angel captive and Castiel must rescue him before Crowley's torture reveals their secrets. Castiel turns to Dean for help. Meanwhile, Sam reconnects with Amelia who asks him to make a choice: stay with her or leave and never contact her again.
Sam and Dean are at odds after Sam asks a hunter named Martin (guest star JON GRIES) to keep an eye on Benny without telling Dean.However, when Martin tells Sam that Benny, might be responsible for a string of vampire-drained bodies in a small Louisiana town,Dean defends his friend. When Martin decides to take things into his own hands, things get messy and Dean is forced to make a veryhard decision.
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!