"Supernatural" has released a well over two minutes clip that reveals how Sam got in a psychiatric ward at the first place. Dean tells the attending doctor that his brother has been talking about the Apocalypse and how he was responsible for it. Sam recounts the real event in the end of season 4 that saw him killing Lilith and unleashing Lucifer.
A former hunter named Martin, who is currently institutionalized, calls Sam and Dean for help investigating a case in the mental hospital. The brothers get themselves admitted as patients to check out the mysterious monster that is attacking the patients, but their incarceration pushes both to the breaking point as they unleash their inner demons against each other.
The preview is for January 21 episode titled "Sam, Interrupted", the first episode of 2010 after Winter break.
On related news, EW has just reported that the may have gotten its cupid for Valentine's Day episode "My Bloody Valentine". Lex Medlin who has starred on "Southland" reportedly will guest star as the Cherub who may cause several couples to start engaging in obsessive, compulsive, and deadly behavior. The episode is to air on February 11.