A girl and her boyfriend run out onto a football field and then go to the bleachers. As they kiss, a noise echoes through the bleachers. They ignore it but a man staggers out, his face decaying. He falls back, sobbing and the students recognize him as Mr. Howard.
Rachel brings her new boyfriend Sam Giradi to the apartment she shares with Nina. He's impressed at her ability to identify all of the ingredients of the meal they had and offers to whip up something with her. They kiss but Rachel reacts badly and asks Sam to go.
The next morning, Nina tries to talk about Sam but Rachel refuses to discuss it. Dr. Rosen arrives with a package. Gary takes the package he has and discovers that it's their badges showing they're members of the DCIS, the Defense Criminal Investigative Service. Rachel slips away to make a call and Rosen inadvertently interrupts her. He figures that it's about Sam and tries to talk to her about it, but Rachel refuses to discuss it with anyone. Rosen then asks her to go with the team to Fenton, Pennsylvania.
As they drive to Fenton, Rosen explains that there have been a series of deaths brought on by acute organ failure. The CDC has been unable to determine the cause so Agent Sullivan is sending in Rosen's team. Rosen and Rachel arrive in Fenton and he admits that they're broadening the scope of their activities. Rachel enhances her smell and informs Rosen that she can smell fear and that everyone in town is scared. They walk through the town and Rachel listens in as the townspeople discuss various rumors of what is causing the deaths. Dr. Vanessa Calder of the CDC meets them and explains that she stayed to handoff the reports to them as the CDC withdraws. She explains that the damage in all three victims centered on the amygdala centers of the brain and they were subject to extreme shock. Calder wishes them well and leaves.
Rosen and Rachel go to the sheriff's department where Coach Kent Zelanski is complaining to Sheriff Marty Handell. As Zelanski leaves, Handell says that there were four deaths, but the fourth one was an unrelated car crash involving Chris Elkhart, a local teen. He admits that there was no autopsy, but Rosen asks to see the body to be certain.
They go to see Chris' mother Jessica to ask permission to exhume her son's body. Rachel notices that Chris father is dead and Jessica explains that her husband passed away when Chris died. He hung out with Jessica and they were very close. Rosen asks if anything odd happened in Chris' life before he died. He wasn't big enough so Zelanski made him the equipment manager. Jessica says that Zelanski is a thug and always yelled at Chris. Chris persisted, refusing to let the team down. Rachel breaks into tears and then apologizes. She continues, telling Jessica that Chris was lucky to have such a loving mother. She agrees to let them exhume the body. Outside, Rosen asks if Rachel is okay with the case and he points out that she's been particularly sensitive since she moved out of her parents' home. Rachel admits that her family won't return her calls and seeing Jessica and her suffering brought it home for her. They go to see Sheriff Handell but get no response. Rachel smells decay and hears a single heart beating. They investigate and Rosen steps on a piece of flesh. Handell grabs Rachel, vomiting on her, and Rosen pulls him off. He tries to get through to Handell, who says that he should have listened and stopped it before he dies.
The next day, Rachel leaves a message for her mother while the rest of the team arrives and meets with Rosen in the local diner. Rosen reports that he found high levels of cortisol in Handell's body. At high concetrations it can eat away the organs. The waitress, Gina, comes over and Gary overreacts, and she figures that the Federal government is involved because a serial killer is at large. Rosen tries to reassure her and she leaves. Bill goes over the file on Coach Zelanski, noting that he's connected to four of the victims. Rosen admits he's not comfortable investigating and Bill offers to take over.
The team goes to the Fenton high school and they split up to check things out. Gary focuses on the transmissions to Zelanski while Cameron accompanies him. As the students stare, Gary confirms that Zelanski sent emails to one of the victims' son, David Burton. Bill and Nina go to talk to the coach and Zelanski overreacts. He insists that his team gives people hope and snaps at Bill. Nina uses her power to tell him to sit down, calm down, and answer their questions.
When the team gathers back, Bill tells the other that Zelanski is a jerk but he isn't the killer. There is one football player whose name keeps coming up for bullying and vandalism. Gary wanders off, checking emails and realizing that everyone hates David Burton, the player in question. He finds David beating up on a student and confronts him in his own unique way, telling him what the other students have said about him in their emails. Cameron arrives and easily takes out David and his fellow players, and Zelanski and his assistant when they assume he started the fight and attack him . David runs off and Cameron trips him with a book. Bill and the others arrive but discover that David is convulsing. Rosen confirms that he's not an Alpha, but another victim. They take David to the hospital while Gary tries to take his letter jacket. Rosen calls Sullivan and asks her to prepare a MRI suite, and then tells the others to check David's activities that date.
At the sheriff's office, the team is unable to find anything unusual with David's activities that day. However, Bill has checked the autopsy and confirmed that Chris Elkhart had no unusual cortisol levels.
At the hospital, Gary arrives wearing David's jacket. Nina objects, but Rosen arrives and informs them that they have flushed David's systems but his body is still generating cortisol. Rosen realizes that David is in withdrawal but there are no foreign substances in his blood. He realizes that all of the victims were addicted to a person, and they suffered lethal withdrawal.
Calder returns to the hospital to check on David. Rosen and Nina meet with her and watch as she takes David's hand. His condition stabilizes and Rosen has her release his hand. He gets worse and Rosen realizes that holding his hand is causing him to generate oxytocin, a love-type hormone. As Calder goes to get oxytocin, Rosen tells Nina that their Alpha created the bond and then severed it.
Rachel goes to talk to Jessica and assures her that they are investigating. Unimpressed, Jessica says that David and his friends beat up Chris and spread rumors on the Internet. He never understood why they targeted him and idolized David and the others. She confirms that Rachel won't be meeting her friends for another 30-45 minutes and offers to make her a snack. Rachel declines and Jessica admits that Rachel reminds her of her son. Upon reconsidering, Rachel agrees to stay.
Cameron and Bill go to the site of Chris' crash. There are no road conditions that could account for the accident and the weather was fine on that day. Cameron analyzes the scene with his hyperkinesis and realizes that it was no accident.
The oxytocin treatment stabilizes David, and Rosen refuses to explain exactly what is causing the addiction. After Calder leaves, David says that he needs to see a female and apologize. Rosen tries to get him to explain who he's talking about but David passes out again. Bill calls Rosen and tells him that Chris crashed on purpose. Handell covered it up and also covered up David's bullying. All of the victims helped in the cover-up. They realize that Jessica is the Alpha and that Rachel is with her.
Rachel talks to Jessica about how her parents think she's a freak. She then explains that she has enhanced senses but that her parents think she's sick because she can't handle any extreme sensory input. Bill calls but Jessica tells Rachel that it can wait and hugs her. As she does, Rachel glows and feels much better.
Bill and Cameron approach the Elkhart house and discover that the front door is unlocked. There is no sign of Rachel or Jessica, and Rachel's cell phone is on the end table. Mrs. Elkhart is driving the blissed-out Rachel, who admits that she can't trust Rosen. She admits that her entire team is Alphas and Mrs. Elkhart says that she'll need her help with one thing before she can escape.
Rosen calls to have Gary track Jessica's cell phone transmissions and warns Nina that Jessica isn't thinking rationally and is suffering from something similar to post-partum depression.
Jessica explains that she killed the victims because of what they did to Chris. She comforted one of the bully's fathers at the funeral and he admitted what his son did. Jessica soon realized what she could do and blamed them for Chris' death. Rachel tries to get through to her and Jessica cuts off the oxytocin, causing withdrawal. She insists that if Rachel helps her, she'll feel better.
Gary directs Bill and Cameron along the roads to cut Jessica off. Bill finally loses control and goes off the road, breaking the axle of his car. Bill floods his system with adrenalin and starts running.
Rachel spots Bill and Jessica realizes that she's seen something. She reapplies her touch and gets Rachel to tell her what she is seeing. Jessica pulls over and gets Rachel out of the car, and then slaps her and says she wants her to die. Rachel collapses, moaning in pain, and Jessica drives off. Bill finds her as she starts to deteriorate.
Jessica goes to see Zelanski, who is glad to see her and figures that he'll feel better now that she is there. She tells him that he and the others murdered Chris and now he'll die alone.
Cameron and Rosen arrive and the doctor gives her an oxytocin injection. It doesn't break the pain cycle and Rosen has Rachel focus on his voice. He tells her that what she's feeling is not love and insists that Rachel is like a daughter to him and always will be. The others join in, telling her that they love her. Rachel manages to generate the oxytocin on her own and recovers.
Zelanski begs for Jessica's love, insisting that he need to make Chris tougher. Jessica is disgusted hearing everyone blame her son and tells the coach to burn in hell. She walks outside just as Rosen and the others arrive. The doctor goes inside while Rachel tells Jessica that Chris wouldn't have wanted her to hurt anyone as revenge for him.
The next day, Rosen tells Rachel that he informed the authorities that Jessica poisoned her victims. Rachel realizes that Rosen is sending her to Binghamton and he worries that it may be the portent of things to come. He asks Rachel how she is and she admits that she's alive thanks to him. Rosen tells her that it was her own ability that saved her life and says that she's more capable than she knows. He offers to take her home and Rachel agrees that home sounds good.