Ep. 12 - Scarlett, Sam and Dean investigate a series of crimes and suicides in Milwaukee, Wisconsin, wherein people are behaving out of character - stealing from their places of business and then committing suicide shortly thereafter. During their investigation, they come across Ronald Reznick, a victim who has conspiracy theories about "Mandroids." His amateur research reveals to Scarlett, Sam and Dean that the perpetrator of these crimes is in fact a shapeshifter.
Plotting out the path of the shapeshifter in congruence with the city's sewers, Scarlett, Sam and Dean pinpoint the next place of attack - City Bank Milwaukee - and pose as security techs in order to view the bank's security camera footage and locate the undercover shapshifter.
They are interrupted when Ronald comes into the bank, chaining the door closed behind him and brandishing a gun. Convincing Ronald that he believes him, Dean helps him lock everyone in the bank into the vault and they seek out the shapeshifter. Unfortunately, the shapeshifter has already changed appearance by this stage, and the tension is increased as it changes appearance multiple times, with Scarlett, Sam, Dean, and Ronald attempting to track it down in order to kill it. Ronald is shot and killed by a police sniper while in pursuit of the shapeshifter.
Meanwhile, the police are stationed outside, and they manage to see Dean's face as he leads an ailing hostage out to an ambulance. Once Dean has been identified, the FBI come in, and it's revealed that an agent has been tracking the Winchesters for some time and knows some details about their history and childhood. SWAT teams infiltrate the building while Scarlett fights and finally kills the shapeshifter. Scarlett, Sam and Dean escape the building by stealing and wearing SWAT team uniforms.
Ep. 13 - Sam, disguised as a nurse, interviews a woman in a psychiatric facility who murdered a man, Carl Gully, and claims an angel told her to do it. Sam returns to a motel room where Scarlett and Dean are as Dean is keeping a low profile after his media exposure during the bank siege in Milwaukee. He relates her story and Dean scoffs at the idea of angels. They proceed to investigate Carl Gully's house, where they find a number of bodies buried.
Overnight another killing takes place - a man kills a stranger and says an angel told him who to kill. Investigating the victim's house, they find evidence on his computer that he was stalking a young girl over the Internet. Scarlett discovers that both victims attended the same church - Our Lady of the Angels.
The siblings visit the church and speak to Father Reynolds, who has nothing helpful for them, until he mentions his fellow clergyman Father Thomas Gregory who was shot on the steps of the church. Both Dean and Scarlett thinks it may be Father Gregory, a vengeful spirit, making people kill parishioners whose guilty secrets he knew. Sam is skeptical; he thinks it may be God at work, and reveals to a startled Dean that he prays regularly.
The siblings return to investigate the church's crypt where Father Gregory is buried. While in different rooms, an angel appears to Sam and tells him he will be given a sign of someone to kill, someone about to do evil.
Dean still thinks it is the spirit of Father Gregory and suggests that they summon his spirit. As they buy the supplies necessary for the summoning, Sam sees the man he says the angel wants him to kill.
Dean takes off after the man and tells Scarlett and Sam to go and perform a séance. They are interrupted by Father Reynolds just as the spirit of Father Gregory appears. Father Gregory thinks he is an angel, but Father Reynolds argues with him and finally puts his soul to rest by saying the Last Rites.
Meanwhile, Dean is following the man Sam had identified, and stops him as he is attacking a young woman. Dean chases him in his car until the man's car nearly collides with a truck. A metal pipe from the truck impales the man, killing him.
Back at the motel, Sam explains to Scarlett and Dean why his faith is important to him. Dean describes how the man died, and says he thinks it may have been the hand of God at work.
Ep. 14 - Scarlett speaking on the phone with Ellen. Sam has been gone for a week. Suddenly, Dean gets a call from Sam. Scarlett and Dean hurries off and finds Sam dazed and covered in blood. Sam tells Scarlett and Dean the blood isn't his and that he doesn't remember a thing.
Together, the siblings follow a string of clues to try and discover what happened to Sam during the missing days. They happen upon a storage unit for which Sam has the key. When they open it, they find a stolen car, and inside the car, a bloody knife on the floor. Clues lead them onward to a gas station where a startled worker demands that Sam leave. Apparently, while Sam visited during the missing week, he began chain smoking and downing beer, even throwing the bottles at the worker's head, a revelation that confuses Dean.
The siblings find themselves at a house and inside they find the corpse of a hunter, Steve Wandell. They watch the security videos in silent horror, seeing Sam grapple with Wandell before slitting his throat.
Dean and Scarlett are thrown off by what has happened, and they worry that Sam might be turning evil. Back at the motel, Sam asks Dean to make good his promise to kill Sam should he turn evil and make sure to stop Scarlett from interrupting. Scarlett can't let it happen, saying, "I'd rather die than to let it happen." To which Sam says, "You'll live to regret it," before knocking her and Dean unconscious.
Dean rouses in the morning, finding that both Sam and Scarlett are gone. He traces Sam's phone to Duluth, Minnesota. Sam has found Jo, in her own equivalent of a road-house. He starts to come onto her and she resists. He knocks her out.
When she awakes, she is bound to a pillar, close by Scarlett as she finally waking up. Sam tells Jo that, "My daddy shot your daddy in the head," in a sing-song voice, revealing that John killed Bill to put him out of his misery.
Scarlett tries to brake off her chains and confronts Sam. Just before Sam can do anything, Dean bursts in, and Sam pleads again for Dean to kill him, or else Sam will kill Jo and his own sister. Dean is unable to go through with it, turning away from an angry Sam who shouts that Dean would rather let innocents die than face life without his brother. Dean suddenly turns around, splashing the contents of his flask on Sam.
It is holy water and it sears Sam, who is revealed to have been possessed by a demon. Demon-Sam escapes through the window and Dean gives chase. The demon taunts Dean that its plan all along was to push Dean far enough that he'd kill Sam and that it'll use Sam's body to find and kill every hunter it can. The chase finally ends on a dock, where demon-Sam shoots Dean, who falls into the water. Thinking him dead, demon-Sam leaves.
Scarlett and Jo quickly finds Dean wounded but alive. Jo fixes him up, taking the bullet out of his shoulder. Jo quietly asks if demons ever tell the truth, to which Dean replies that they can occasionally if they know it will get to a person, but Jo refuses to reveal anything more than that. She offers to help, but Scarlett and Dean forbids her to follow.
Demon-Sam turns up at another hunter's home, Bobby Singer. Bobby lets Sam in and offers him a beer, toasting to John Winchester. As Demon-Sam drinks up, he suddenly collapses, smoke coming out of his mouth. Bobby reveals that he'd mixed the beer with holy water and tells him, "Don't try to con a con man" before knocking him unconscious.
Demon-Sam wakes later to find himself in the center of a devil's trap. Dean and Scarlett are already there, and Bobby starts the exorcism. The demon inside Sam snarls viciously at the chant and Dean tells it that no matter what kind of plans that the Yellow-Eyed Demon has in store, he and Scarlett will not let anything happen to Sam. The demon laughs at him and says that it being there has nothing to do with the "Master Plan". Bobby's incantation fails to expel the demon, which gleefully begins its own incantations. Bobby finds a binding link on Sam's arm, which effectively locks the demon inside of Sam and neither he nor Dean or Scarlett know what to do next. Meanwhile, Demon-Sam's incantations affect the devil's trap on the ceiling, cracking it to pieces and finally allowing the demon access to its powers again.
Sam turns back to Dean and Scarlett, eyes now black, and flings them and Bobby using telekinesis. He pulls himself free from the chair and starts to give Dean a beating, punching him viciously and squeezing his injured shoulder.
Scarlett grabbed the demon, pulling it away from Dean and punching it in the face. The demon grabbed Scarlett's waist, pushing her to the wall and it smirked as it said, "You can't hit me, My Unicorn." Reveals itself to be the same one that possessed Meg, who has crawled out of hell, bent on getting her revenge. Meg tells Scarlett that no matter how much she tortures her and Dean, it's nothing compared to the way Scarlett tortures herself over losing their father and over potentially losing Sam.
Suddenly, Bobby grabs Demon-Sam's arm and burns the mark on Sam's forearm with a hot iron rod, destroying the link. Sam screams as the demon exits him and escapes via the fireplace.
Later, the three are sitting at Bobby's place nursing their wounds when Bobby informs them that Steve Wandell has been murdered and that his hunter comrades are out looking for blood. He tells the siblings to keep their mouths shut about it. Bobby also gives the siblings charm amulets to prevent future possessions before Scarlett, Sam and Dean hit the road again.
Along the road, Sam reveals to Scarlett and Dean he was awake for some of the things that Meg did in his body; he was even awake to watch Steve Wandell being murdered by his own two hands. He also rebukes Dean for not taking action and killing him when asked, as this could have been the moment their father warned Dean about before his death. Scarlett tells him that John told Dean he'd either have to save Sam or kill him and they will definitely find a way to save Sam in the end.
Ep. 15 - Scarlett, Dean and Sam investigate the apparent suicide of an adulterous professor on a university campus. The local urban legend that seems most likely the culprit turns out to be a bust. Then a frat boy is humiliated when he reports being abducted by an alien. Puzzled, and increasingly antagonistic with each other, the siblings fail to find any answers when again another urban legend appears to come to life - a scientist who used animals in his experiments is killed by an alligator in the sewers.
Unable to make headway, Scarlet, Sam and Dean call Bobby, who comes to the town to help them out. Bobby listens to Scarlett, Dean and Sam's stories about the case, and their irritations with each other, and works out that a Trickster is at work. They track down the most likely culprit - a janitor in the campus building where the deaths occur. The Trickster attempts to bargain with Dean in order to escape, but the four hunters manage to trap him and a fight ensues before Dean stakes the Trickster in the heart. After the four leave the building, the body Dean staked disappears and the real Trickster appears; seemingly, it has used its ability to manifest things out of thin air to deceive the hunters into thinking they were killing it. As they leave town, Scarlett, Sam and Dean reconcile in a touching scene - much to Bobby's disgust.
Ep. 16 - Molly McNamara and her husband David are driving along Highway 41 in Nevada when they see a man standing on the road. They swerve to avoid him, crashing off the road. Molly wakes up in the car, smashed in the woods, but David is gone. While trying to find him she comes upon a house. The man she saw on the road appears, bloodied and eviscerated, and he pursues her. Molly runs back to the road and flags down a car - driven by Scarlett, Sam and Dean.
She explains her story to them, but when she tries to show them her wrecked car, it's gone. Scarlett, Sam and Dean agree to take her to the police, but as they are driving, a man appears on the road. Rather than swerve, Dean drives at the man and he disappears. The siblings explain to Molly that the man is Jonah Greely, and he was killed on this stretch of road fifteen years ago. He haunts the road and each year on the anniversary of his death, finds someone to punish. They explain that in order to stop him they must find his body and salt and burn his bones.
With Molly, they find Greely's hunting cabin. Jonah tries to grab Molly, but Dean dispatches him with a blast of rock salt from the shotgun. The party then find a house in the woods. While searching it, Scarlett and Molly find a photo album and letters belonging to Jonah and his wife, showing they were very much in love. Scarlett explains that ghosts, even vengeful ones like Jonah, in life may have been good people. Dean and Sam find the body of Jonah's wife, who killed herself out of grief after Jonah's death.
Jonah returns and grabs Molly, taking her to his cabin to torture. Scarlett works out that Jonah is buried near the house with a tree as a grave marker, and she and Sam starting to dig while Dean goes to rescue Molly. As Jonah fights Dean, Sam and Scarlett exposes his corpse and salts and burns it.
The siblings take Molly into town and show her that her husband is alive - and married to someone else. They reveal to Molly that she died fifteen years ago, in the car accident that killed Jonah Greely. Molly has been unable to accept that fact and has continued to relive that night. Finally she accepts the truth, and she disappears as the sun rises.
Ep. 17 - Scarlett, Sam and Dean travel to San Francisco to investigate violent deaths that they suspect are due to a werewolf. They visit Madison, a lawyer's assistant (possibly secretary, or a paralegal), whose boss was the latest victim. She admits that he would hit on her occasionally, and that the night of his death she spotted her violent ex-boyfriend Kurt watching them at a bar.
The siblings find signs of werewolf activity near Kurt's apartment and discover the body of a dead police officer in a nearby alley. For Madison's safety, Scarlett decide Madison needs protection - a job for which Sam and Dean are keen to volunteer. A game of Rock, Paper, Scissors results in Sam being left to guard Madison while Dean is out investigating Kurt with Scarlett. There is an obvious attraction between Sam and Madison, and while Madison flirts, Sam is shy and they spend the evening watching TV until Madison goes to bed. During the night, unnoticed by Sam, Madison transforms into a werewolf and sneaks out to kill Kurt. Dean and Scarlett bursts in on her and Scarlett manages to nick her with a silver blade before she knocks her and Dean out.
Sam interrogates Madison and figures out that Madison was infected when she was bitten during what she thought was a mugging a month previously. Sam finds lore in John's Journal that suggests that if the "sire" of someone who is a werewolf is killed, they will be released from the curse. While Sam guards Madison, Scarlett and Dean visiting the area of town where the previous victims were attacked. Dean saves a young woman from an attack by a werewolf, which Scarlett kills. As it dies it reverts to human form and is revealed as Madison's neighbor Glen.
Scarlett, Sam and Dean stay with Madison through the next night; she doesn't transform, and they assume she has been cured. Buoyant at this outcome, Sam and Madison consummate their attraction with a session of passionate lovemaking. But that night, as the full moon rises, Sam witnesses Madison become a werewolf again before she flees the apartment.
The next day, Madison calls Sam, scared and confused. When Scarlett confirms gently as possibly that they have no way to cure her, Madison begs Sam to kill her, because she doesn't want to live as a monster. While distraught and reluctant, when there appears no alternative, Sam, despite his siblings' offers to do it instead, kills Madison.
Ep. 18 - On the set of the movie Hell Hazers II: The Reckoning, directed by McG, a stagehand is killed and the star of the movie, Tara Benchley, reports seeing an apparition near the body.
Dean and Scarlett convinced Sam to come to Los Angeles for a break after the death of Madison, but Sam wants to throw himself into work. Dean, a movie buff, becomes enthusiastic when he discovers the movie is a horror movie starring one of his favorite actresses, Tara.
It doesn't take the siblings long on the set to discover that the stagehand's death was faked by the studio executives to promote interest in the movie. But then a studio executive, Brad Redding, dies in the middle of the set after encountering a ghost. Dean goes undercover, joining the crew as a P.A., a job he embraces. The siblings discover that a young actress killed herself in the 1920s after being wooed and then dumped and fired by a studio executive. They find her buried at the Hollywood Forever Cemetery, where they salt and burn her bones.
After another producer, Jay Wiley, is killed, Scarlett notices that the Latin in the movie script is a real summoning ritual. They confront the writer, Martin Flagg, who admits that any authentic rituals in the script are all that remained from the original script by writer Walter Dixon.
Dixon lures Flagg onto the set to kill him, but Scarlett, Sam and Dean arrive in time to save him. Walter admits that he was conjuring real ghosts and forcing them to kill those he saw as responsible for ruining his script. Before they can stop him, Walter destroys the talisman he was using. This frees the spirits who, enraged at being used, turn on Walter and kill him.
The production of the movie continues, with Martin incorporating his experiences with the ghosts into the script. Scarlett and Sam finds Dean emerging disheveled and with a post-coital glow from Tara's trailer. Scarlett, Sam and Dean walk off into the sunset together - until it is wheeled away and revealed as just another Hollywood prop.