Supernatural is about two brothers, Sam and Dean Winchester, who are on a crusade trying to track down and destroy paranormal creatures. The show was renewed by The CW on February 24, 2009.Blogcritics.org: Supernatural Renewed for Season Five (February 25, 2009)

Season 5 premieres on Thursday, September 10, 2009 at 8/9c, paired with the new vampire drama The Vampire Diaries, starring Ian Somerhalder and Paul Wesley.http://www.cwtv.com/shows/supernatural

It all started when Dean Winchester (played by Jensen Ackles) and Sam Winchester (played by Jared Padalecki) were both kids; Sam, an infant and Dean just four years old. In the early morning of November 2, 1983, Mary Winchester, their mother, was murdered by a demon known as "Yellow Eyes". This demon wants Sam to be the leader of an Army of Demons (we later find out that Yellow Eyes dripped demon blood into Sam's mouth when he was a baby, right before killing his mother).

Years later, Sam joins his brother, Dean, to find their father who is missing. Sam then finds out that Dean and his father have been hunting demons and other paranormal creatures all these years, hoping to find Yellow Eyes. They later find their dad and the three of them continue their quest. However, when they do run into Yellow Eyes, Sam and Dean's father gives his soul to Yellow Eyes in exchange for saving Dean's life.

At the end of Season 3, Dean sells his soul to the "Cross Roads Demon" in order to bring Sam back to life after he is killed. Dean is sent to hell and spends 30 years there (but only 4 months go by on Earth). Dean is freed from hell by Castiel, an angel who needs Dean's help to stop the apocalypse.