"This is my Father's world, and to my listening ears, all nature sings and round me rings the music of the spheres…" In Harringtonville, Tennessee, a young boy with a beautiful soprano voice is having a voice lesson. His teacher is very proud of him, and, as they finish the lesson she asks her teen-aged son to walk the boy, Wally, home. As they walk away from the house, it seems someone is watching the teacher through the window. A figure wearing a hooded sweatshirt enters the house and kills the music teacher.
At the BAU, JJ and Hotchner bring the team up to date on the two killings in the small town in Tennessee. The first victim was a grandfather named Paul Thompson who was ambushed in his yard with 18 stab wounds to his chest and neck. The only item stolen from his house was a shotgun. The second victim, Annie Stewart (the music teacher) was ambushed and bludgeoned to death in her home with the stolen shotgun. This time, many smaller items were stolen from her home. There were different MOs and different weapons were used on the two victims. Gideon enters on crutches and wonders if there were two different killers. He's hurt his ankle skydiving and can't go out into the field while on crutches. The disorganized crime scenes suggest a psychotic killer – and they won't be able to predict his behavior without an understanding of his particular delusion. Reid finds a clue – bloody rings at the crime scene may be a signature.
In Tennessee, Elle and Reid are going over the crime scene at Annie Stewart's home. Drugs were missing from the medicine cabinet which leads Reid to believe one unsub may be suffering from delusions caused by methamphetamine addiction. Considering what the thief did and didn't take, they believe there were two people in the house: the killer is a psychotic, but the other one was just a thief, and probably knew the victim. From Wally's position during the singing lesson, Elle can tell that he could see the unsub outside the window based on the position of a soda can the sheriff's department found outside. When she talks to Wally and his mother, Wally tells her he looked "Crazy. Real tall, real skinny and his lip was bleeding."
At the sheriff's office, Sheriff Hall and Deputy Long look into "tweakers," methamphetamine users, in the area, as Reid and Elle have told them the one who lives closest to the victims is almost surely who they're looking for.
Back at the BAU, Gideon has decided to camp out in Garcia's computer room, spreading out crime scene photos and reference books all over her neat work area. She tries to get him to go back to his office, but he is very focused on the case. He moves her stuff around looking for blueprints of the house, he asks her to fix the heat, get the autopsy reports – she is frustrated but tries to do as he asks, mumbling as she walks away.
Hotchner and Morgan arrive at the sheriff's office. They didn't find anything at the Thompson house. Sheriff Hall and Deputy Long narrow the suspects down to Domino Thacker – "serious tweaker who cooks his own stuff" and lives almost directly between the crime scenes. The team heads to Domino's house, where Domino, in his underwear, tries to get away. Morgan chases him down and arrests him. At the jail, the team interrogates him, telling him all the evidence they have against him: the blood on his boot is Annie Stewart's and the boot tread matches prints inside her house. Domino admits he went to the house as "he" was leaving, a man with a black hood, then he went in and stole things. He says Annie Stewart "was already like that, all cut up."
Hotchner and Morgan don't believe Domino killed anyone. "Anybody delusional enough to eviscerate Annie Stewart would not be lucid enough to recount it the way he did."
Back in Garcia's office, Gideon is eating chicken and broccoli as Garcia brings in the autopsy report. The victim was missing her liver and stomach. As Gideon picks up his take-out, it leaves a brown ring on the blueprint he had set it on. Garcia begins to complain about the mess he's making in her office, but he ignores her. He puts the container down and picks it up again, and notices these rings match the rings from the crime scene photos. The unsub is removing organs from the body and putting them into containers. "It's anthropophagy – the literal translation is 'man-eating.' This guy's a cannibal."
In Tennessee, the BAU gives local law enforcement the profile of a twenty to thirty-year-old male. He believes he must eat human flesh or drink human blood. Reid mentions the Vampire Killer, Richard Trenton Chase, who drank his victims' blood because he thought aliens were draining his blood. This man has an extreme psychosis; he can't venture far from home. Something about his delusion is keeping him in town. The team wants to recanvas the town, but Paul Thompson's funeral is that afternoon, so they will attend and watch the townspeople.
After the funeral, JJ shows Hotchner the files of local men with criminal histories. One is Oley Maynor who was institutionalized years ago for severe manic-depression and once bit the heads off chickens. He was released from an institution just a few weeks before. A woman at the funeral, Mrs. Mays, mentions that she has seen him in town, with his brother, and that the two of them were acting as if they didn't want to be seen.
At Jess Maynor's butcher shop, Jess is wielding a large cleaver as Elle, Morgan and the sheriff enter. Jess denies that Oley is in town, but a noise comes from the back room. Morgan finds Oley hiding in the walk-in freezer with a meat-hook. Oley has been staying with Jess and Jess has been protecting him from the people in town who always laughed at him. Oley has only come home to say goodbye, he is planning to go live in a special home, and insists he is innocent. He gives the team some of his hair so they can test it to make sure he's been taking his meds.
Wally is at his grandmother's house, and is singing for her. Wally then watches TV as his grandmother gets cookies out of the oven and goes into the laundry room. Someone is waiting for her there, with a knife.
When the BAU team and the sheriff's department arrive, the grandmother is dead, and Wally is missing. A neighbor reports seeing the grandmother's car race out of the driveway 25 minutes ago. Wally's mother screams at Elle, that it is her fault because Wally spoke to her about the unsub. Morgan feels the unsub may have been after Wally all along. Reid and Hotchner examine the body – it has been eviscerated, too. Reid finds the unsub has split her ribcage open and has taken her heart.
Gideon clumps down the hall on his crutches to Garcia's office. Speaking on the phone with Reid and Hotchner, he discusses the significance of the organs the unsub has taken – liver, stomach and heart. These had special meanings to different ancient civilizations; they were each thought to be the seat of the soul at one time or another. And when he drinks their blood he "believes he is encountering the divine." He has even left the bodies in such a way as to resemble angels. Why kidnap Wally? Gideon believes he sees the boy as a messianic figure.
Annie Stewart's husband pulls up outside his home. Neither he nor his son has returned since Annie's murder. Opening the door, he finds a container on the floor containing human organs. When the team arrives, Hotchner discovers that it is a human stomach. Reid explains to Sheriff Hall that some disorganized killers return body parts in order to manipulate the body even after death, but "it may also be an act of remorse." Hotchner asks the sheriff to post an officer at every church in town as the unsub may be feeling guilty about what he has done.
Elle and Morgan are staked out at a church when a car matching the description of Wally's grandmother's pulls up. A figure holding a bag gets out and approaches the statue of an angel. After he is in custody, Elle pulls a blood filled container out of the bag.
The unsub is Eddie Mays, 21, and he is extremely psychotic and delusional - out of control. There is no way the team can question him about Wally in his current state. Sheriff Hall tells Hotchner that the Mays' family is one of the oldest in the area, and very respected. His mother is the woman they met at the funeral. She cannot believe her son could do anything like this, and she didn't even know he was in town. Mrs. Mays signs the consent form to allow Hotchner to give Eddie an anti-psychotic injection so they can ask him about Wally's location.
Garcia tells Hotchner that Eddie had trouble in college, where he majored in comparative religion. Eddie got into methamphetamines and rock cocaine and suffered a mental breakdown because of it. He checked himself out of the hospital and made his way home a week ago. When Hotchner asks her how it is having Gideon around she responds, "Ah, you can have him back whenever you'd like."
At the Mays' house, Elle and Morgan realize that Mrs. Mays must have OCD – she is obsessively clean and neat – and they can find no signs of blood or other evidence. The smell of bleach is strong in the utility room, and, moving the empty refrigerator, they find the tell-tale bloody rings on the floor.
After Eddie receives his injection, Hotchner and Reid attempt to question him. He is still very confused. Although he recognizes a picture of Wally, he cannot understand what is happening. When he is shown pictures of the victims, he becomes more agitated and repeats over and over again, "Please, I brought you an angel, please." The team leaves Eddie alone to discuss their options, and Eddie tries to hang himself.
Hotchner knows Mrs. Mays has been hiding her son, and tries to get her to admit it, but she won't. She continues to deny knowing he was in town, or that he needed help. She claims the blood on the utility room floor is from cutting herself when she prunes her roses. Checking the GPS in her car, the team discovers that she has stopped at the same place on Route 3 six times. They decide to drive Mrs. Mays to that spot, telling her they are going to see Eddie in the hospital. Hotchner makes small talk with her in the car to keep her off balance. When they arrive at the rural location, Hotchner tells her he thinks she was protecting her reputation by keeping her son's illness a secret – even if she had to keep the authorities from finding Wally to do it. He asks for her help now to find Wally, but she doesn't respond. The sheriff's department arrives with dogs, and they find Wally in a shack – alive and safe.
Mrs. Mays asks Hotchner if there was anything he wouldn't do for his children. He answers, "I wouldn't clean the blood of their victims off the floor," and continues, "Every day of your life you're going to have to ask yourself, what would have happened if you'd gone to Boston to help him." Deputy Long takes her away.
Back at the BAU, Garcia is toting the "third box of crap" that Gideon left in her office down the hall to his office, and she's not happy about it. And, she adds, "Everything smells like soy sauce!" Hotchner assures her he'll take care of it and takes the box into Gideon's office. Gideon is looking at his life list, his list of 25 things he'd like to do before he dies. Skydiving was #24 so he decides he needs a new list. Hotchner encourages him to "do them all." Gideon replies, "He doesn't want to hear from me." But as Hotchner leaves, Gideon dials the phone. "Steven? It's your dad."