A hunter, Lee Chambers, is having coffee at a truck stop for the second night in the row. As a waitress, Sally, flirt with a driver outside, the other waitress Marlene approaches Lee, serves him coffee, and makes conversation with him. Sally goes off with the driver and Lee follows her, drawing his knife. He loses them between the trucks and suddenly feels dizzy. Marlene comes up behind him and admits that she drugged his coffee with her venom, and then knocks him out when he tries to fight her.
In the aftermath of Bobby’s death, Sam and Dean sit at his home and mourn. After a couple of weeks, Dean begins trying to decipher the five-digit number that Bobby gave them as he was dying. He begins collecting articles on Dick Roman, trying to figure out a pattern. He finally calls Frank Deveraux with the info and wait for the conspiracy theorist to get back to him.
Meanwhile, Sam gets out a beer and suggests that they call Bobby’s people, pointing out that there’s no one else to do it. Bobby’s phone ring and Sam answers it. It’s a girl, Krissy Chambers, who asks for Bobby. Sam admits that Bobby isn’t there and Krissy hangs up. He wants to look into the call but Dean figures that waiting for Frank’s call is more important. As they argue, Dean discovers that his beer bottle is empty, even though he doesn’t remember finishing it off. Sam gets him to agree to find him once Frank calls and then goes to check on Krissy.
At the Chambers apartment, Krissy reluctantly lets Sam in once he explains that he got her phone number and then her location from Bobby’s address book. He admits that Bobby is dead but insists that Krissy can trust him, and she finally lets him in. She tells Sam that her father Lee, a hunter, hasn’t checked in with her in five days. Sam goes through Lee’s goods and discovers that he has a hidden collection of articles on the disappearance of drivers at the truck stop. Figuring that Lee kept his vocation from Krissy, Sam tells the girl that he’s going to follow up a lead and says that he’ll check back in a couple of days. Krissy notes that her father said the same thing.
Dean gets a call from Frank and meets him at a safehouse in the country. Frank greets him armed with a rifle and figures that Dean is a shapeshifted Leviathan. Dean finally cuts his arm to reveal that he doesn’t bleed black goo and then has Frank does the same. Once they’re both satisfied, Frank takes Dean to the RV he’s using as a mobile base of operations and explains that Dick and his Leviathans have been tracking him down ever since he started researching them. Dean insists that Frank give him the answer on the number, but Frank explains that Bobby was dying and didn’t give them the complete number set. Running a probability check, he’s found the missing sixth number and confirmed that the number is a coordinate to a field in Wisconsin, owned by Richard Roman Enterprises. Frank reluctantly agrees to go there with Dean and run surveillance.
Sam goes to the morgue and checks out the corpse of one of the dead truck driver, Matthew Halvena, who was ripped apart by something with teeth. He calls Dean who is at the field at Wisconsin and tells him what he’s found, and Dean tells him what they’ve discovered. After Sam explains that Krissy doesn’t know Lee is a hunter, Dean hangs up and helps Frank. The two men are posing as telephone repairmen and Frank sends Dean up to tap into the camera lines. They go back to the RV and Frank tells Dean that they’ll have to wait until someone shows up and that he should get some rest. Dean dozes off, unaware that his cell phone is ringing.
After checking John’s journal, Sam leaves a message that the killer is a Vetala, and that John killed a one several years ago after it fed slowly on its living prey. Sam then goes to the diner and talks to Marlene, unaware of who she really is. She directs him toward Sally and Sam goes out into the parking lot to talk to her. Sally claims that she hasn’t seen Lee but says that they’re being watched and takes Sam off to the side. Once they’re alone, Marlene attacks Sam, who tells Sally to run. However, Sally transforms into a Vetala as well and the two creatures easily knock Sam out.
Dean wakes up and discovers that over a day has gone by. Frank shows him surveillance footage of a woman, Amanda Willer, who is surveying the field and work for Dick. Dean grows increasingly impatient and Frank suggests that he go out and kill something, and warns that he’ll drive himself crazy if he doesn’t relieve his stress. When Dean wonders what Frank did, he explains that when he was 26, he discovered that a creature had gutted his wife and two children. He put on a smile and vowed to act professional, one week at a time. Taken aback, Dean discovers that Sam left him a message about the Vetala and realizes that the information from John’s journal about the creature being a loner is wrong. Krissy calls him, having got his number from Sam, and tells Dean that Sam hasn’t checked back with her.
Sam wakes up and discovers that he’s been tied to a chair in an abandoned building. Several dead men are scattered around the room, and Lee is tied to a chair but still alive. He explains that the Vetala used their venom to keep them paralyzed so that they can feed at their leisure, and that a human can only withstand four feedings... and the Vetala have fed on Lee three times.
Dean goes to the Chambers apartment and looks around, trying to make sure Krissy doesn’t see any of her father’s hidden research. All he finds is a torn piece of map and realizes that Krissy knows all about her father’s job as a hunter. Krissy explains that she figured Sam could handle things so she played along with his assumption she didn’t know. However, now it’s clear Sam can’t handle it. Krissy draws a gun on Dean when he demands the map, and he insists that he’s going to rescue both men. He easily disarms her but Krissy tells him that she burned the map after memorizing it so that he has to take her with him.
As they drive to the truck stop, Dean refuses to answer Krissy’s questions because he says he’s not in the mood. However, he finally tells her that the Vetala were able to capture Sam and Lee because they had both read John’s journal and thought that the creature were loners. Dean knows better because he killed one while Sam was at Stanford and never told his brother about it. Krissy is surprised to learn that any hunter could have a normal life.
Sally comes in to check on Sam and Lee, and then prepares to bite Lee for the final time. To save the other hunter’s life, Sam provokes Sally into biting him by claiming that he tortured and killed one of her kind.
As Dean and Krissy stake out the truck stop, Dean wonders if the girl has had any experience hunting. He soon realizes that she hasn’t and that he can tell she’s scared. When Krissy insists that Lee has trained her, Dean warns that all the training in the world doesn’t prepare a hunter for their first hunt. Marlene gets into a truck and Krissy spots her, and they follow her to the abandoned building. Dean congratulates Krissy and offers her a fist-bump, much to her disgust. However, when she reluctantly goes along, he handcuffs her to the steering wheel and tells her that he’s not taking a kid in. Krissy begs Dean to let her come inside, explaining that she saw her mother turn to shreds by a creature. He still refuses and takes her hidden lockpick, and then heads for the building.
Inside, Dean finds Sally and Marlene preparing to feed. He attacks Sally, stunning her, but Marlene struggles with him. Krissy runs in, having managed to get out of the handcuffs, and Sally grabs her to use as a hostage. Dean reluctantly releases Marlene while Lee complains that he brought Krissy there. Sally orders Dean to drop the life and he agrees, asking that they spare the girl. While Marlene feeds on Lee, Sally prepares to kill Krissy. However, she stabs the Vetala with a hidden knife, killing it. Marlene goes for Dean but Krissy cuts Sam free and gives him the knife, which he uses to kill Marlene.
Later, Dean and Sam visit Lee at the hospital. They talk to him privately and he tells Lee to quit so that Krissy can have a normal life. When Lee explains that he got into hunting because a creature killed one of his family, Dean tells him that he should get out of hunting for the same reason. Lee isn’t convinced and asks if Dean has ever known a hunter who went back to a normal life and Dean tells him that they all died before they could.
As the brothers leave, Krissy runs up to them to say goodbye. Dean realizes that she used a bobby pin to free herself, but the girl says that she’s retiring and might go to college like Sam. Krissy jokingly tells Dean that he’s lame but fist-bumps him and walks away.
As the brothers drive through the night, Sam wonders if Dean is all right. He tells his brother that they should just work and figure out a way to take care of the Leviathans. Sam suspects that something is wrong but accepts Dean’s assurance and goes to sleep. Meanwhile, Dean tries to smile like Frank suggested, without much success.