As the Apocalypse approaches, Castiel and Zachariah inform Dean that his moment of glory draws nigh. Sam, disagreeing, goes with Ruby to take on Lilith.
Sam is locked in Bobby's panic room to cleanse his body from demon blood. However, after several seals are broken Bobby wants to set Sam free to help stop the Apocalypse and Dean seeks out Castiel for help.
Dean has a dream about Castiel asking to meet him in private. Sam and Dean are shocked to discover Castiel's human host, Jimmy, is back in control. Jimmy wants his life back but Sam and Dean believe he is in danger.
Sam and Dean are on a hunting trip when they receive a call from an Adam Milligan, who is trying to find John Winchester. They discover that Adam was conceived 19 years ago when his mother fell in love with John Winchester.
Sam and Dean come across a series of novels called Supernatural depicting their lives as demon hunters in detail. The brothers meet the author of the comics, Chuck, who explains he has visions of Sam and Dean in action then puts their adventures in his novels.
Dean and Sam now lead ordinary lives. Dean works in the corporate world at the Sandover Bridge & Iron Company along with Sam who works as a Tech Support. Both have no idea who the other is until their colleagues start killing themselves.
Sam and Dean seek help from Pamela, who sends the brothers to the spiritual realm. They discover Alastair attempting to break the seal causing mayhem in the mortal world by stopping death from occurring in a small town.
Sam and Dean are faced with magicians delving in black magic. They investigate after several people wind up dead in ways similar to the illusions the magicians perform on stage.
Sam, Dean, and Ruby look for Anna who hears the voices of angels. When Ruby seemingly betrays the brothers and leaves with Anna, Sam enlightens Dean on how Ruby saved Sam's life while Dean was in Hell.
Sam and Dean meet Castiel and his fellow angel Uriel, who warn the brothers to avoid intervening in a town where a witch is attempting to summon the demon Samhain, opening one of the Seals.
Sam and Dean investigate the mysterious deaths of several men who seemingly died of fright. Dean becomes infected with it starting as anxiety then leading to a full-blown terror which ends in death. Sam and Bobby race against time to save Dean.
Sam and Dean find Jack, who is changing into a Rugaru, a flesh-eating demon that preys on humans. Sam and Dean have a disagreement on how to deal with Jack.
Dean gets transported back in time and ends up in Lawrence, Kansas, where he crosses paths with a young version of his parents, who have just fallen in love.
Ghosts of children Bobby couldn't save cripple him with guilt and Sam and Dean must save him. However, they must also ignore the spirits of Meg and Agent Hendricksen, who have come back to accuse the brothers of failing them.