Scott's phone vibrates, waking him up. It's Stiles. At first he only hears breathing, but then Stiles whispers a terrified, "Scott?" Stiles is terrified, and he tells Scott that he doesn't know where he is or how he got there. Scott asks Stiles to describes what he can see, but it's dark and he can't see much.

 

The line drops. Scott calls back twice, getting voicemail each time. He gets more and more agitated and waits for Stiles to call back. When he does, Stiles tells him that he can't move. "Something's wrong with my leg. It's stuck on something. And it's . . .  I think it's bleeding." 

 

Scott keeps asking if Stiles is there and if he can hear him. Stiles says there's a smell where he is that's so brutal it's making his eyes water. Scott wants to call the Sheriff, but Stiles begs him not to. He says that his dad has been so worried already. Scott won't promise not to call the Sheriff because he's not sure if he'll be able to find Stiles on his own. 

 

Stiles hangs up, telling Scott he'll call right back. Scott starts throwing on clothes and yells for Isaac to wake up. Isaac comes rushing in and asks what's wrong. Scott tells him to get dressed because something's wrong with Stiles. "What's wrong with Stiles?" "I don't know."

 

At the school, Lydia is in the art room sketching Aiden, who volunteered to be her model. He rolls his neck and drops his pose. "I said hold still," Lydia tells him. Aiden wonders if they're allowed in the school that late, and Lydia explains that with so many murders happening at the school they can't even find someone to take a late night security shift. "So we're all alone?" Aiden asks with a smile. Sitting around fully clothed wasn't what Aiden had in mind when Lydia asked him to model for her. He takes off his shirt and resumes his pose. 

 

Lydia grins at him. "If you're thinking nude modeling, it's usually done without the pants," she says. And next thing she hears is his zipper coming down. Aiden starts to take his underwear off too, but Lydia hears voices. She stares at the radio and hears Stiles begging someone to come find him. 

 

As Scott and Isaac are running out of the house, Scott's phone rings again. Stiles asks if Scott called his dad. Scott reports that it's just him and Isaac. He asks Stiles again for details about where he is. "It's a basement. I think . . . I think I'm in some kind of basement." It's big, so he thinks it's industrial. There's a furnace, but it's cold. Stiles says that he has to turn the phone off because it's going to die. Then Scott realizes something. "Stiles, why are you whispering?" "Because I think there's someone in here with me," Stiles replies, his voice shaking.

 

Kira is at home studying. Her lightbulb goes out, and she calls for her mom to come replace it. When Kira touches the bulb, it briefly lights again. She does it more deliberately the second time, energy flowing out of her fingertips and into the bulb. When she touches the glass, it explodes. 

 

Mama Yukimura comes in and asks Kira what she did. Kira tries to cover for herself, and her mother tells her she should be asleep because it's after midnight. She replaces the bulb, and a little electricity bleeds off of her into the bulb. They both pretend they didn't notice it. 

 

Scott and Isaac go to Stiles's room and find Lydia and Aiden already there. Scott asks her if Stiles called her, too. "I heard it," Lydia says. Aiden tells them not to ask because it gets more confusing when you ask. "Not as confusing as this," Lydia says and turns so they all can see that the red cords from Stiles's evidence board have been tied to a pair of scissors impaled in his mattress. She explains that Stiles uses red for unsolved cases. "Maybe he think he's part of an unsolved case," Aiden offers. "Or is an unsolved case," Isaac says. 

 

Lydia asks why they're there, and Isaac and Scott explain that they came to his room to get a better scent. Stiles told them he's in an industrial basement, he's bleeding, and he's freezing. "Tonight's the coldest night of the year," Aiden says. "It's going to drop into the 20s." When Lydia asks what the Sheriff had to say, Scott is forced to admit that they haven't told him. Lydia is incensed. But because she didn't make any promises, she calls. Aiden points out that Stiles's Jeep is gone, so he didn't just walk somewhere.

 

Scott tries to stop her. He'll call Derek and Allison. "Everyone except for the cops. Great idea!" Aiden points out that Lydia only gets banshee feelings when there's imminent death, so they don't have a lot of time to mess around. Scott agrees to head down to the station, which is only 5 minutes away.

 

Lydia tells him that she has to stay. She's convinced there's a reason she was led to Stiles's room. "There's something here." "Yeah. Evidence of total insanity," Isaac says. Scott doesn't quite know what to say to that, so he focuses on finding Stiles rather than trying to figure out what's wrong with him.

 

Stiles turns the flashlight in his phone on. He sees that his leg is caught in a steel trap and screams. He sobs and tries to move. "Who's there?" He shines the light around, looking for the person who he can hear in the basement with him. He spots someone with their back to him, writing on the wall. It drops the piece of chalk it was using, and Stiles watches it roll. When he looks back up, he sees the onore kanji written on the wall. Someone has told him about the symbol, so he knows it means "oneself."

 

The symbol on the wall appears to have eyes, as well. Then it vanishes into smoke. 

 

At the station, the Sheriff tries to hold himself together. He tells Scott that they should start with Stiles's Jeep. The Sheriff orders Deputy Jordan Parrish to put out an APB on a blue 1980 CJ-5. He tells Deputy Cordova that he wants a list of industrial buildings with basements or sub-basements that Stiles could have gotten into while sleepwalking. Stiles could already be hypothermic if he's outside barefoot in a t-shirt.

 

The Sheriff brings Scott and Isaac into his office and asks them if there's anything they need to tell him that he can't share with his people. "That Lydia knew he was missing." The Sheriff asks if she can help find him, and Isaac replies that she's working on it. Scott reveals that he called Derek and Allison for help. The Sheriff asks if Scott can track Stiles by scent, but then Parrish comes in and reports they found the Jeep.

 

The Jeep is parked at Beacon Hills Hospital. The battery is dead. "Why would he come here?" Scott asks. "Let's find out," the Sheriff replies. They head into the hospital, and Melissa says that  security is sweeping every floor, but they haven't found anything yet. The Sheriff asks about the basement, and she takes him.

 

Derek is up on the roof. Scott and Isaac hurry up to catch him. "He's not here. Not anymore," Derek says. Derek has searched the whole building. Isaac goes to tell the Sheriff. Scott asks him to find Allison, because she's not answering her phone.

 

Scott moves to stand next to Derek. Derek asks him if he's noticed how strong the scent is up there. "Ever hear of chemosignals? Chemical signals that communicate emotion. And just our sweat can give off anger, fear or disgust. Take a deep breath and tell me what you feel." Scott does and reports that he feel stress. "And anxiety," Derek confirms. He doesn't know what Stiles was doing up there, but there was some kind of struggle. "With who?" Scott asks. "Himself," Derek replies.

 

Rafael McCall goes into the sheriff station and asks Parrish where everyone is. He asks if they have any leads on the guy that stabbed him with a sword. "Nope, but we've got posters up all over town for your guy," Parrish says, glancing at a wanted poster for Zorro over his shoulder. Agent McCall complains, and Parrish says he isn't a high priority. McCall asks him what is. 

 

Aiden and Lydia continue going through Stiles's things. Aiden finds one of Lydia's nemeton sketches framed. She tells him to put it back. "He likes you a lot, doesn't he?" Aiden asks, clearly poking fun at Stiles's crush. Lydia makes him stop. She gets a text from Scott informing them that Derek is heading to the high school while Isaac goes to find Allison. Scott is going to stay with the Sheriff. 

 

Bored, Aiden plucks one of the red strings. Lydia turns suddenly, hearing voices. "What did you just do? Did you just touch one of the strings?" Aiden looks guilty. "Maybe." Lydia cautiously plucks one of the strings herself. She asks Aiden if he heard people whispering. "I definitely did not hear people whispering." She tries again and Aiden says "Lydia, I'm not sure anybody hears what you hear." She follows the whispers and the string to an image of Eichen House. It's the mental health center where Barrow was committed.

 

Lydia tells Aiden that that's where Stiles is. 

 

Stiles's phone has run out of power. He tries to get the trap off his leg, but it won't open. He screams at the other person in the room, demanding to know who they are. He answers in Japanese. When Stiles tells him that he can't understand, he switches to English. "Not, who are you, Stiles? Who are we?" 

 

The wrapped man asks Stiles if he's noticed that it's getting colder but they've stopped shivering. It's a bad sign. "It's the body trying to conserve energy. It was my fifth grade science report. Hypothermia." Next his speech with thicken. Then fatigue and confusion. "We're going to die if we don't get out of here." Stiles tells him to stop saying we, but the wrapped man tells him that he's trying to keep them from freezing to death.

 

He tells Stiles to get up, and Stiles shouts at him that there's a steel-jawed trap on his leg. The creature asks him if there really is. He asks if something's different. Wasn't the trap on his right leg before? Suddenly the trap is on Stiles's left leg. Stiles asks the creature what it's doing. "We're trying to save you, Stiles. We're trying to save your life."

 

The Sheriff, Scott, Lydia, and Aiden arrive at Eichen House. The Sheriff asks Lydia if she's sure. She swears that he is. They rush in and tell the front desk that they need access to all the basements in the facility.

 

Back at the sheriff station, Agent McCall asks Parrish if the transcript is exactly what Stiles told Scott. He wants to know if the quote "Something smells terrible, my eyes are watering" is accurate. Parrish can't really help him but assumes it's accurate. Melissa shows up at the station because her shift was over. She wants to help.

 

Lydia leads the way in Eichen House. "It's here. It's right here." The Sheriff opens the basement door and they all rush down, but Stiles isn't there. They all look to Lydia for an explanation. The Sheriff turns angrily at her, demanding to know where Stiles is. They all leave, without noticing that onore kanji carved into the wall.

 

Melissa and Agent McCall are in the car. Agent McCall thinks Stiles might still be asleep. He points out that people can do crazy things while sleepwalking, like cooking and mowing the lawn. He starts to explain how there was one night when he came home drunk. "Oh, one night?" Melissa snarks. McCall asks if he can finish. "So I'm drunk, passed out on the bed. I get up to go to the bathroom. Then suddenly I hear you yelling 'What the hell are you doing?'" Melissa laughs. "Because you were in the closet peeing into the laundry basket." Which is exactly his point. He was convinced that he was in the bathroom, just like Stiles is convinced he's in a basement.

 

Agent McCall thinks he knows where Stiles might be.

 

The wrapped man tells Stiles that it's a riddle. He asks if he knows any.

 

"What gets bigger the more you take away?"

"A hole." "

 

"What gets wetter the more it dries?"

"A towel."

 

"When is a door not a door?"

"When it's a jar."

 

"Everyone has it, but no one can lose it."

 

Stiles doesn't know the answer to this one. The creature keeps repeating the question, and Stiles sobs that he doesn't know. The creature shouts in his face in Japanese. It grabs the trap and starts dragging Stiles across the floor. He screams and claws at the ground.

 

The cement beneath his hands shifts into dirt, He screams, "Wait! No, wait!" as Agent McCall and Melissa haul him out of Malia Tate's den. Melissa holds him like his father did when he woke up screaming from a nightmare. 

 

Isaac beats on Allison's door. When she opens it, he asks, "What the hell have you been doing?" "Sleeping. What the hell are you doing?" Isaac asks her if she got any calls or texts, and Allison discovers that her phone is off. This is strange because she never turns her phone off. She turns it on and gets a flood of messages. Isaac tells her that they found Stiles a few minutes ago. 

 

Allison notices a lot of strange calls and voicemails. She plays one, and it's someone speaking Japanese. 

 

Aiden starts Derek's car while Derek sets jumper cables up on Stiles's Jeep. He asks if Derek thinks Stiles was just sleepwalking or if there was something more to it. "In this town, there's always something more." Aiden says that he listened in on Stiles telling Scott that he thinks he was the one who wrote the message in the Chemistry room. "You think Stiles, skinny, defenseless, Stiles, is the nogitsune? A powerful dark spirit?" Derek doesn't believe it. Aiden claims that he's not the only one thinking it, just the only one saying it. "This thing wants to possess someone and chooses Stiles? Why not take someone bigger, stronger? Someone with a little more . . ." Derek stops as he has a realization. "Power." He touches the jumper cables together, making a spark.

 

In the hospital, Agent McCall, Melissa, Scott, and Lydia wait for the Sheriff to come back with news. He tells them that Stiles is sleeping and is fine. He thanks Agent McCall. "It was that repellent we sprayed in the coyote den to keep other animals out. I couldn't go near it without my eyes watering." Agent McCall deflects the thanks, so the Sheriff says it again and eventually has to tell McCall to shut up and take his gratitude. The two shake hands.

 

Melissa sends Scott and Lydia head home because they've got school in less than 6 hours. As they leave, Lydia apologizes for having led them the wrong way. She turns suddenly at the sound of metal clanking, but she chooses to ignore it because her powers just betrayed her. 

 

At school the next day, Scott texts his boss to see if he can be of any help. "Still working on it," Deaton replies. As he leaves the locker room, Kira calls after Scott. He ignores her, though. Derek appears and tells Kira that Scott's a little preoccupied. Derek offers to help Kira if she'll show him everything that happened at the power station with Barrow. 

 

At the hospital, Melissa tries to tell the Sheriff her suspicions about Stiles's condition. He stops her from having to voice her fears by showing her his notebook, where he's made the same list of symptoms. He can't quite look her in the eye when he says, "I think we need to do some tests." 

 

At the power station, Kira shows Derek where Barrow had her. He sees a divot carved in the concrete and follow it up to Stiles's metal bat, stuck to some machinery. Somehow, Derek knows that the bat belongs to Stiles, even though he's never seen him with it. It takes a bit of force for Derek to rip the bat down. The bat's magnetized. (Note: You cannot actually magnetize an aluminum bat.) He places the bat at the beginning of the divot a moves it along, mimicking what must have happened when the electricity struck. "Kira, I'm gonna need you to tell me everything you know about foxfire," Derek says.

 

Back at the school, Allison and Isaac ask Ken Yukimura to listen to the voicemails on her phone. He says that the man speaking is giving instructions. "All evacuees are required to stay at least 10 feet back from the outside fences." Isaac asked what fences, and Ken Yukimura explains they're the fences around a Japanese internment camp during World War II. The man in the recording is reading instructions to prisoners upon their arrival to one of the camps after the attack on Pearl Harbor. Ken Yukimura says that the recording is fake because it mentions Oak Creek as the internment camp, but there was no such camp. 

 

Lydia is next to Scott as his locker, and she winces as someone closes their locker door. Scott asks if she's okay, and she lies and says yes, but she's hearing everything far more loudly than she should. Scott tells Lydia that they're doing tests on Stiles all afternoon and he'll be going to visit at 6 if she wants to come. Lydia tells him that she'll just go home. Another locker closes, and Lydia reacts like it was a gunshot. She rushes out of the school.

 

In the hospital, the doctor claims to not know how to pronounce Stiles's name. He's not even sure if it's a misspelling. The Sheriff tells him to just call him Stiles.

 

Stiles is sitting on the bed of an MRI machine with Scott right next to him.  The doctor warns him that the MRI is going to make a lot of loud sounds. He offers Stiles earplugs or headphones, but Stiles refuses. "Hey, we're just on the other side of that window," the Sheriff says. Melissa McCall is right at his side. Stiles pats his dad's arm, and the parents leave the room. "You know what they're looking for, right?" Stiles asks Scott. "It's called frontotemporal dementia." Scott gets tears in his eyes as Stiles explains that the dementia causes areas of your brain to shrink, and it's what his mother had. "It's the only form of dementia that can hit teenagers. And there's no cure." 

 

Scott wipes a tear away. "Stiles, if you have it, we'll do something. I'll do something." It's clear that Scott is offering the Bite to Stiles if he needs it. They hug each other tightly while their parents watch.

 

Derek pulls up to the hospital with Kira. She isn't sure she should go in. "You're gonna tell Scott that Barrow might have used foxfire created by me to jump start the nogitsune's power inside Stiles." Which means she basically helped a dark spirit take control of his best friend. Derek agrees that maybe she should wait outside. 

 

Inside the hospital, they load Stiles into the MRI and tell him not to move. The doctor starts the machine, and it makes the sound of a hammer hitting an anvil. Elsewhere, it having suddenly become dark out, Lydia sits in her car hearing the same sound. She tries to drown it out with loud music, but it's not working. 

 

Derek and Scott sit in the waiting room to talk. Scott tells him that the lesson about chemo signals earlier reminded him of the time Derek tried to teach him about having an anchor. Derek sort of smiles and figures Scott taught him that time. "Are you teaching me again?" Scott asks. "Think of it more like sharing a few trade secrets." He tells Scott that he took Cora back to South America and also found a way to talk to his dead mother. "She told me something that changed my perspective on a lot of things. She said my family didn't just live in Beacon Hills. They protected it. This town needs someone to protect it. Someone like you." Scott gives Derek a kind look. "And someone like you to teach me a few trade secrets." Derek smiles a little at that.

 

Scott has a revelation. "He was trying to protect us. Stiles was protecting us." "From himself." Derek and Scott race up to the roof. Scott thinks Stiles's struggle was more than just metaphorical. He thinks he was struggling to not do something. Scott reaches up on one of the structures on the roof and finds a bag of electrical equipment. They look around trying to determine what Stiles was doing, and Scott spots a wire that's been damaged.

 

Lydia can't take the sound anymore and screams in her car.

 

The doctor, Melissa, and the Sheriff look at the results of the scan. It shows atrophy, which is proof that Stiles is ill like his mother was. 

 

In the machine, Stiles starts getting more and more upset. He presses his eyes shut and wakes up inside a dream. The nogitsune asks him if he's figured out the riddle yet. If he answers correctly, the nogitsune might consider letting his friends and family live. He claims they're going to destroy everyone he's ever cared about, one-by-one. Stiles cries and asks him why. 

 

The nogitsune repeats his riddle: Everyone has it but no one can lose it.

 

Stiles repeats that he doesn't know. The nogitsune starts taking off his wrappings. Stiles shouts that he doesn't know. But then he figures it out. A shadow. As he turns around, he sees that the nogitsune is himself. 

 

Stiles wakes up on the MRI, but it's the nogitsune in control. He makes the power flicker, and while everyone is looking elsewhere, he gets up and leaves. "Where's my son?" the Sheriff asks.

 

On the roof, a transformer box explodes. A live power line starts whipping around.

 

The nogitsune casually gets dressed as people run around the hospital in a panic. An elevator door opens revealing Noshiko Yukimura. The nogitsune recognizes her and goes to confront her. "You know me," she says. The nogitsune nods. "Then you remember that I won't be deterred by your choice of host. Even if it's an innocent boy." The nogitsune asks if she's threatening them, and Mama Yukimura calls two Oni to her side. "Now I'm threatening you," she says. The nogitsune tells her that they're not really afraid of her fireflies. 

 

Noshiko announces that if the Oni can't defeat him, she knows someone who will. The nogitsune turns and stares at her. 

 

Outside, Kira watches as the live wire from the roof whips down toward her.