Though he wants nothing to do with his family's paranormal investigation business, a Stanford junior pairs up with his estranged brother on a road trip from the Bay Area to Los Angeles when their father goes missing. Along the way, they encounter mysterious people and situations from American myths and legends.
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.
Sam and Dean are on a hunting trip when they come across a guy named Adam Milligan. Later they find out Adam was conceived when his mother fell in love with a hunter who just so happens to have been John Winchester.
Sam and Dean come across a series of comics called Supernatural depicting their lives as demon hunters in detail. The brothers meet the author of the comics, Carver Edlund, who explains he has visions of Sam and Dean in action then puts their adventures in the comics.
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.
Angels get slaughtered by Lucifer's sword. Castiel and Uriel hold Alastair captive and ask Dean to use his newfound techniques in torture to take valuable information that can put an end to the murders. Dean learns some shocking facts from Alastair.
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.
A siren casts a spell on Sam and Dean while they are on a mission in Iowa, leading to their violent behavior.
Sam and Dean investigate a haunting at one of the high schools they attended as teenagers.