Sam now is forcing Dean to back off, if not stop from his obsession on Dick Roman, and get more focused on doing their usual jobs. They find an unusual case involving similar murders that happen every few years in various places, eventually linking them to Cronos, the Greek Titan of Time (Jason Dohring). However, as they chase him down the alley, Dean accidentally "hitches a ride" on Cronos, who drags him back to 1944. While Dean pairs up with Eliot Ness (Nicholas Lea), who is a hunter as well, Sam pairs up with Sheriff Mills, in finding a way to bring Dean back to the present and kill Cronos. Dean is able to get a message to Sam. After tracking down the girl that Cronos fell in love with who's now an old woman, Sam and Mills learn that Cronos grabbed Dean and disappeared at 11:34, so they plan to summon him from that particular time. Dean and Eliot get a stake that can kill Cronos and reveal the truth to the woman he loves. Sam summons Cronos as he tries to kill Dean and Eliot tosses him the stake as he goes. In the present, Sam kills Cronos with the stake, but he warns that their future is filled with black ooze [it refers to the Leviathans] and that the Leviathans are everywhere. He tells them to enjoy oblivion.
Source: Wikipedia
Source: Wikipedia