On this week's episode of Supernatural…
Sam, Dean, and Bobby attempt to figure out how to kill (or at least slow down) the Leviathan that they've captured. Nothing they normally use works.
Sam and Dean learn that a pair of Leviathan look like them and are going on a killing spree in the order of their hunts since Sam left Stanford.
Sam and Dean attempt to intercept the impostors, but end up captured instead.
Sheriff Jody Mills arrives at Bobby's place and thanks him for saving her. While cleaning she accidentally drips water mixed with borax onto the Leviathan. It burns him enough to slow him down and Bobby chops off its head separating the two pieces.
Sam and Dean defeat impostor Sam and Dean in similar fashion, except fake Dean reveals that Dean killed Amy.
Crowley attempts to team up with the leader Leviathan, but he refuses.
Sam, now upset and betrayed, leaves Dean.