 In "Goodbye Stranger", Castiel has been completely brainwashed by Naomi and has killed thousands of copies of Dean ruthlessly.Castiel is sent to find the angel tablet and tortures and kills the demons also looking for it, drawing Sam and Dean's attention.Sam and Dean track down someone who knows the location of one of Lucifer's Crypts where the angel tablet is and in ensuing scuffle, Sam ends up in trouble.