Professor Hayden Parker is at his home recording a podcast about The Blood and its charismatic leader, former decorated soldier Billy Grimm. Parker talks about Grimm's preachings and how he's a messianic charlatan. As he talks, Kelly comes in with Rebecca, one of Billy's people. Kelly explains Rebecaca's husband was one of the people who kidnapped Kelly's sister, and he killed himself rather than talk. The agent figures that Rebecca knows where her sister is and claims that Rebecca is under arrest. She wants Parker to help convince Rebecca to reveal what she knows, pointing out that he deprogrammed her. as they talk, the lights go out and Rebecca chuckles in the darkness .Several men storm in, tase Kelly unconscious, and leave with Parker and Rebecca.
At Nate's apartment, Jeff goes over his brothers' notes on Cult[/]. Someone sends him an email saying that her husband was abducted just like Nate and asks for the reporter's help.
Skye is out at the ranch where they film the Cult ranch scenes. She gets some research on ballistic trauma for Marti to read so she can get into character. She gets a text message from Jeff and the makeup artist, Lexi, asks if she's going off to be with him. Lexi points out that everyone has seen the two of them together and have been gossiping about it. Sky insists that there's nothing sexual between them. When Lexi goes to get some water, Marti asks about Jeff and Skye insists that they just have a shared interest.
At Fandomain, Jeff is going over the files on the show when Skye comes in. She manages to get his attention and he explains that she met the woman, Alma, on a Cult fan site. They agreed to meet a half hour ago but there's no sign of Alma. Skye warns him that Alma may be a True Believer but he says that he had to take the chance. They notice a man, Terrence Ross, who keeps staring at them, and he finally comes over and notices Nate's notebook next to the computer. He asks Jeff if he's a fan and Jeff says that he is, and Terence figures that Jeff isn't one of them.
Terrence then gestures and Alma comes in. Once Terrence assures her that Jeff is okay, the woman sits down with Jeff and Skye. She explains that she and her husband Rami live in Indianapolis and watched Cult from the start. Rami soon became obsessed with the show and received strange calls about the show. He went missing ten days ago after receiving one of the calls. People broke into their home and Rami went to investigate. Alma heard voices and saw him leave with the intruders. The police dismissed her concerns, pointing out that Rami left voluntarily. Terrence is a deprogrammer who finds people lost to cults and brings them in.
Alma shows them Rami's notebook, which has references to Los Angeles and True Believers. Alma and Terrence came to LA and started checking the fan chat rooms, and finally located Jeff. Skye goes through the notebook and finds a black disk like the one that Nate had. Alma says that when she inserted it into a computer at work, it flashed images but didn't do anything. Skye figures that since Alma didn't use a personal computer, the disk didn't compromise it. Jeff figures that it may not have erased itself and Alma agrees to let them take it. Terrence refuses, saying it isn't going anywhere without him.
Jeff and Skye leave with Alma and Terrence, and the reporter calls E.J. to tell her that he's bringing her the disk. Terrence isn't convinced that he can trust E.J. and insists on following them. As Terrence and Alma go to their car, Detectives Sakelik and Zavala pull up. While Zavala talks to Terrence, Sakelik asks how Jeff knows Terrence and the reporter claims that he's doing a profile on the man. The detective warns Jeff that Terrence has been implicated on assault and kidnapping charges. Sakelik claims that Terrence passes himself off as a self-styled cult deprogrammer and tells Jeff to stay away from the man while she does her job and finds Nate. Once Sakelik leaves, Skye wonders who they should trust and Jeff thinks they shouldn't trust anyone.
E.J. meets the group at Nate's apartment and goes to work on the disk. Alma notices Nate's wall of clippings and admits that her husband had a similar one. She asks about Nate and Jeff admits that it's just the two of them. Meanwhile, Skye asks Terrence about his training in deprogramming and he says that he's never received formal instruction. When she points out that it's a TV show, not a cult, Terrence points out that it's just like one. E.J. cracks the disk and brings up a series of 3D images. She digs further and brings up the IP address where the disk was burned. E.J. recognizes the place as a hacker hostel where some of her friends stay. She gives them an address and Jeff, Skye, and Terrence go to check it out.
Billy lectures a group of cultists on how and when to take a life. He then takes out a knife and slaughters a pig for food. Once he's done, he meets with his men as they bring Parker in. Billy cuts the man loose, wipes his blade off on the professor's jacket, and says that they should wash up before they eat.
Sakelik is watching the episode on her iTouch when Zavala comes over to the car and tells her that they'll have a wiretap on Terrence's phone in an hour. When her phone rings, Sakelik fakes dropping a cup of coffee in her lap. Zavala goes back in to get some napkins and Sakelik calls her people. They tell her that they moved Nate to a new location, and she brings up a photo of Nate on the police car's computer.
Billy takes Parker out to the middle of a field and enjoys roast pig. Parker warns the cult leader that he won't get away with it, but Billy continues eating and invites Parker to call him Billy. He tells Parker that he thought it was time to meet his unauthorized biographer. Parker realizes that Billy has his manuscript and warns him that everyone knows that if he disappears, he was writing about Billy. Billy insists that he's never harmed anyone and admits that he's impressed with Parker's attention to him. Parker, his hands nailed to the table, refuses to respond.
Jeff, Terrence, and Skye got to the hostel and find a dozen hackers all at work. The reporter notices one of them, Sean, making black disks and points him out to Terrence. The hacker quickly packs up and tries to run off, and Jeff grabs him. The other hackers either run off or attack. Sean runs for a car and Terrence shoots him with a rock-salt load. The deprogrammer hauls Sean to his car and calls Alma to tell her that they have a lead. When Jeff and Skye object, Terrence says that they'll talk to the hacker for an hour and then let him go. He warns them that they're dealing with bad guys and asks Jeff what he's willing to do to save his brother. The deprogrammer gets in the car and drives away. Jeff prepares to drive off after him, telling Skye that he may not have another chance to find Nate. He suggests that Skye stay behind, but she insists on going with him.
Terrence takes Sean to a rented apartment and Alma meets him there with Jeff and Skye. The deprogrammer gives him an amobarbital injection, assuring the others that he knows what he's doing. Jeff reluctantly helps Terrence despite Skye's objections. Skye goes out on the balcony and waits, and Jeff finally comes out and tells her that Sean isn't saying much even with the drug. She worries that things are turning dark and Jeff admits that he has concerns. However, he insists that he has to follow it through to find Nate. Terrence comes out and tells them that Sean will only say "under a tree" over and over. The deprogrammer figures that Rami is buried somewhere and goes back inside to take Sean somewhere to let him sleep it off. Sean is muttering verses and Skye recognizes them.
Billy shows Parker his three-square tattoo and explains about the significance of the box in many cultures.
Skye brings up the episode video and asks Sean if the tree in the background is the one that he's talking about. Sean says that it's "at the show" and that no one at the ranch knows. Skye tells them that she thinks she knows where the tree is.
Billy takes out a photo of his son Michael and tells Parker that he buried him there at the ranch. The cult leader explains that everything is because of Michael, and starts flipping through the manuscript pages. He finally stabs it and demands to know why Parker didn't say anything about Michael. Parker insists that the book is about Billy, but Billy says that he has to talk about family because that's central to everything he does. He then shows Parker photos of the man's family and stabs them with his knife, and tells Parker that he will never write another word about him.
That night, Skye takes Jeff and Terrence to Guthrie Ranch, where they film the compound scenes for the show. Jeff spots an old drainage pipe leading to a septic tank and explains that he used to vacation on a horse ranch with his parents before they died. The kids there played in an old septic tank and they look for the access hatch. Terrence finds it and they discover that there's a new ladder leading down into the tank.
At the LA police department, Sakelik gets Sean released and has him confirm that Terrence was the man who abducted him. Sean also confirms that Skye and Jeff were there, and admits that he doesn't remember what he told them. He finally admits that he told them about the ranch.
At the ranch, Jeff, Skye, and Terrence discover a series of underground tunnels. Photos of people are taped to the walls and each one has an X through it. Jeff finds a photo of Nate and figures that his brother was down there. They hear someone moaning and Jeff runs ahead to investigate. He finally locates the missing prisoner... Rami. He insists that he's not finished and they find several glowsticks. Rami insists that he needs them to finish the puzzle. Jeff realizes that they're UV glowsticks, lights one, and turns on the light. The walls are covered with words and symbols, and Rami complains that now he can't reach the next level. As they examine the walls, the group hears cars pulling up outside. They quickly get out with a reluctant Rami as the True Believers move in. Jeff wants to stay but Terrence points out that they're outnumbered and heads for the car.
Kelly visits the compound looking for Parker and Billy's people reluctantly let her through. She finds Parker, who insists that nothing happened. Kelly offers to take his statement but Parker claims that he can't identify the people who abducted him. He tells Kelly that Billy didn't do anything to him and walks away. Kelly sees Billy, who nods to her, and reluctantly drives off with Parker.
The next day, Skye goes back to the ranch. Once she's sure no one is watching, she takes some photos of the tunnel... which has been filled with concrete.
At Fandomain, Alma thanks Jeff for getting her husband back and tells the reporter that Nate is lucky to have someone looking for him no matter what. They go outside where Terrence and Rami are waiting, and Terrence admits that Jeff did good. He warns the reporter that he may have to trust some people that he doesn't want to, and says that he'll be in touch. As he prepares to drive off, Terrence admits that the whole thing got under his skin because there's a TV in every home.
That night, Skye tells Jeff that someone sealed in the tank. They try to work out what is going on and figure that the True Believers send the disk to possible recruits and then take them to the tank. Jeff points out that there's no X on Nate's photo, meaning he made it through the initiation, and figure that he's still alive.