In California, Sam and Dean go into a bank. Dean goes to the counter and flirts with the teller, Megan. Once he has her attention, Dean draws a gun and Sam blocks the door, and they tell everyone to get into the vault. Once they have everyone inside, Dean winks at the active security camera and then the brothers open fire, killing everyone inside.
Bobby tries to torture the spell-bound Chet without success when the brothers arrive. Chet informs them that Edgar walked away from them after they dropped a car on him. Dean asks how he found them and Chet readily informs them that he tracked their aliases, and they know the aliases from Castiel’s mind when they possessed his body. The Leviathan assures them that nothing he tells them will do any good because there’s nothing they can do to him or his others. He then tells them that they should watch the news. They tune into a broadcast about how Sam and Dean slaughtered the people in the bank. Chet tells them that they got hold of some hair samples from a shower drain to clone them. Sam figures the Leviathans want to drive them underground and make them vulnerable, and the brothers prepare to go after their duplicates. Bobby warns against it but when the brothers insist, Bobby sends them to Frank Deveraux, who he describes as a nut but one who owes him a favor.
The brothers stop at a gas station but the cashier recognizes Sam from the newscast and goes in back to call the police. Sam realizes that the man is onto them and quickly leaves with Dean.
FBI special agents Valente and Morris follow Sam and Dean’s trail as they move across the country. They get a report that the Winchesters have been spotted and head out after them.
Dean and Sam arrive at Frank’s house but no one answers the door. They go inside and find Frank, holding a gun on them. He accepts that they’re the real Winchesters and demands to know who sent them. When they explain that Bobby sent them, Frank is less than thrilled but they remind him that Bobby saved his life and he owes him. Frank disposes of their IDs and suggests they go into hiding. They refuse and Frank gives them new aliases, tells them to stop using rock shoutouts for aliases, use cash, and change their phones regularly. He then smashes their laptop, gives Sam a new one, and demands $5,000 for the replacement.
Bobby continues to try and kill Chet, who finds it exhilarating. The Leviathan continues taunting him until Bobby snaps and decapitates him.
Frank gives the brothers a map with all the towns that they’ve hit, but tells the brothers they should lie low. They refuse and Frank tells them to at least ditch the Impala, much to Dean’s shock, and warns them that their doubles also have an Impala.
As Bobby prepares supper, Sheriff Jody Mills arrives at his doorstep. She has beer and thanks him for saving her at the hospital, and tells him to accept gracefully. Jody offers to clean and help him settle in. Bobby accepts and goes downstairs, only to discover that Chet’s head has reattached itself to his body. He grabs a machete and decapitates the Leviathan again.
Dean and Sam are driving through the night in their temporary car, much to Dean’s disgust. Sam realizes that their doubles are hitting the towns that they originally investigated after Sam returned to hunting, in the same order that they handled the jobs. They realize the next case would be in St. Louis, and Dean remembers a diner there with the best burgers.
The evil Dean and Sam are at the diner, trying the food with disgust. The two Leviathans talk about their originals and how flawed they are, and then figure it’s time to turn up the heat. They tell a teenager to capture them on his cell phone video and then pull out guns and tell everyone to get on the floor.
Bobby calls to give Sam and Dean an update, but admits that they’ll have trouble getting close enough to decapitate their opponents. When they hear Jody talking in the background, they realize that Bobby has a woman there but he denies it. Bobby tells them that the doubles have moved on from St. Louis, and they realize they’re heading for Ankeny, Iowa.
Valente and Morris watch the video of “Sam” and “Dean” killing everyone in the diner, ending with the teenager holding the camera. The brothers then address the camera, saying that they’re heading for Iowa.
As Bobby tries electricity on Chet, he brushes against the Leviathan’s arm and it takes on his form. The evil Bobby talks about all of Bobby’s many problems
The brothers arrive in Ankeny and spot their evil twins, but the Ankeny police capture the real Winchesters before they can move in. As Sam and Dean are hauled away, they realize that their doubles set them up.
The evil Bobby continues to torment the real one, saying that he’s not the cynic that he pretends and has hopes to end up with Jody. As Bobby prepares to decapitate him again, water drops down from the ceiling and hits the Leviathan, causing his skin to burn. Bobby runs upstairs and discovers that Jody is cleaning the floor. He kisses her, much to her surprise, and asks what was in the bucket.
The Ankeny sheriff puts Dean in a cell and Sam in the interview room, and then sends the other two officers home for the night. As they leave, the evil Sam and Dean watch them. They kill them, take on their forms, and go back inside to kill the other officers on duty.
The sheriff comes to see Dean, who demands a phone call. When he gets it, he tries to tell Bobby what happened without telling the sheriff too much. Bobby says that a chemical, sodium borate, burns the Leviathans, and tells Dean to find anything with borax in it. The sheriff ends the call, figuring that their sickos, and ignores Dean’s plea to find all of the borax. However, when he goes to the squad room, he sees two of his “men” eating the others, and then watches as they revert to Sam and Dean. The sheriff goes back and frees Dean, realizing that he was telling the truth.
Evil Dean finds Sam in the interview room and tells him who he is.
As Dean checks out the dead officers, evil Sam finds him. His gun has no effects and evil Sam slaps him down.
Evil Dean tells Sam that he could be anything and he’s wasting an opportunity to subjugate the weak.
Dean grabs a fire axe but Evil Sam warns that he can’t get close enough to use it. The sheriff douses Evil Sam with borax and Dean decapitates him.
Evil Dean finally tells Sam that Dean killed Amy, relishing the shock of his announcement. As it prepares to eat the now properly-seasoned Sam, Dean breaks in, hits it with borax, and decapitates it. The sheriff frees Sam and warns that the FBI is on its way, and Dean asks him to help fake their deaths. As they clean up, Dean realizes that something is wrong but Sam says that he’s fine.
Later, the sheriff and his daughter, the town coroner, meet with Valente and Morris. The sheriff informs the agents that the brothers were immediately cremated, much to the agents’ surprise. They’re not happy but decide to accept it, avoid the paperwork, and close the case.
As Jody prepares to leave, Bobby thanks her and says there’s one more thing. He hesitates, and then gives her Chet’s severed head and asks her to toss it in the river. Bobby kisses her on the cheek, and Jody smiles and leaves.
The sheriff’s daughter is examining the bodies and tells her father that she doesn’t know what the black goo is. Valente comes in and says that it’s more than blood, and then transforms into a Leviathan and eats them. He then calls his boss, who has taken on the form of a businessman named Richard Roman, and tells them that he’s lost the Winchesters. Valente suggests that they duplicate the Winchesters again, but Roman feels that it would strain credulity. He tells Valente to come back in so they can reconsider their approach.
As Roman gets into his limo, he finds Crowley waiting for him. The King of Hell gives him some muffins with baby uvulas as a welcoming gift and suggests that they consider a merger. Crowley points out that he helped bring them there, but Roman says that he hates demons more than humans and will never work with him. Crowley tells him to keep the muffins and teleports away.
As Sam and Dean dispose of the decapitated heads, Sam remains silent. Dean asks him what is wrong and his brother finally tells him that he knows that he killed Amy. Sam tells his brother that he can’t be around him right now and that he should go on without him. After a moment, Dean agrees and drives away.