Previously on Teen Wolf, Melissa McCall (RN, MD, PhD, DVM) diagnosed Stiles with a lethal form of insomnia and drugged him up so he could get in one good sleep before he died. Ethan and Aiden followed Scott around begging to be in his pack, and when he continued to refuse, they took their lead from Derek Hale and jumped through the windows in his living room to help him fight some Death Eaters. Chris Argent remembered when he was somehow even sexier than he is right now and then took Allison and Isaac to meet a buddy of his, good old Silverfinger, who told them the Death Eaters are called Oni and the Oni are in Beacon Hills to destroy the Nogitsune. And when Stiles woke up from his hospital slumber, he wandered around the hospital barefoot, and destroyed some Oni with his bare hands. Just reached into the total darkness of their shadow bodies and ripped their firefly souls right out.

Scott wakes up in the middle of the night because his phone is buzzing and buzzing because Stiles is on the other end and he is freaking the heck out. He whispers to Scott that he doesn't know where he is, but that it's dark, and he's trapped, and he's cold, and the stench is overwhelming. He hangs up and calls back three times, more frantic by the minute. It's terrifying, actually. It's one of the most terrifying things Teen Wolf has ever done and I'm including every time Danny is on screen, which is always harrowing because he's a gay man of color who has survived far too long in this hell demon town. Scott begs Stiles to give him some hint about where he is, but Stiles has to go again; he's not alone, wherever he is.

Scott starts hollering Isaac's name and Melissa bangs on the wall and tells them to keep it down in there, for the love of Neil Patrick Harris. When Isaac smashes through the door all bleary eyed, Scott tells him to get his scarf: they're going on the most important rescue mission of their lives.

Lydia and Aiden are hanging out in the art classroom at Beacon Hills High, the former doing the painting and the latter trying to make it into a nude modeling session. In a hilarious moment of meta commentary, Aiden wonders where the security guards are and Lydia says so many people have been slaughtered in this school, no one will take the job anymore. Aiden ain't scared. He drops his trousers but is immediately cockblocked by the sound of Stiles' voice coming through some radio speakers asking for someone to save him. And get used to that, Aiden, because Lydia likes your whole banging body, but she loves Stiles' soul. (Also she doesn't even know what he's packing underneath his t-shirts because she hasn't been to Tumblr.) Anyway, they bounce to go do some superheroics.

Kira is doing some homework in bed and when her light bulb goes out she starts yelling for her mom to come change it for her. At like midnight. Very rude on a couple of levels, there, Foxfire. When her mom comes in to replace the bulb, her fingers glow with electricity the same way Kira's do when she gets close to things that plug in. She looks at her mom like maybe she can help her solve the mystery of what's happening to her body, but her mom is like, "The mystery that is solved is GO TO BED."

Scott and Isaac and Lydia and Aiden meet up in Stiles' bedroom where he has stabbed a pair of scissors into the middle of his bed, a zillion string of red yarn tied to the handles and affixed to the unsolved mysteries on his murder board. Scott promised Stiles he wouldn't call his dad, but Lydia made no such promise and operates on an intellectual frequency outside of Scott's realm of understanding, so she says she'll call him, thank you very much. Scott backs down and agrees to hit up Sheriff Stilinski at the station while Lydia stays behind with Aiden to do some voodoo on Stiles' stuff.

Right, so Stiles is definitely in a cold, dark basement. And his foot is definitely caught in a bear trap. And there's definitely some kind of mummy in the corner, breathing menacingly, and drawing that backwards "5" on the wall that the Oni tattoo onto people's ears when they're not possessed. Stiles writes and cries and shines his phone's flashlight all around and breaks everyone's hearts into a gajillion pieces and also: goosebumps on top of goosebumbs. This is some sinister business.

When Scott tells Sheriff Stilinski what has happened, he allows himself one moment of panic, and then he shifts into kick-ass mode, putting out an APB on Stiles' Jeep and pulling everyone off of whatever murder investigation they're working on — and don't you doubt for a second that every single one of them is causing a different Beacon Hills homicide — to find his kid. Stiles' Jeep is at the hospital, but he is long gone. Inside, Melissa tells the good sheriff that maybe she should have mentioned it earlier, but Stiles is definitely dying of the same Brain Cloud that took his mother's life. Outside, Derek has joined up with the search team because of course he has, and he picks up Stiles' left behind pheromones before even Scott because of course he does, and he explains that Stiles was definitely on this roof and definitely feeling an overwhelming sense of anxiety about it.

Aiden rifled through Stiles' shit, mocking the the little love shrines to Lydia all over the place. He thinks it's just so sweet, that unrequited affection Stiles has for Lydia. She shushes him, though, plays a little ditty on the red murder board yarn likes it's a banshee banjo, and discerns that Stiles is being held at some French Quarter-looking asylum where William Barrow spent his days before he tried to electrocute a Lightning Oni. She and Aiden zoom over to the asylum to meet up with the rest of the Get Along Gang — minus Allison, who isn't answering her phone — but what they find in the basement is nothing. No Stiles. No bear traps. No horrifying mummy men. They also do not find the Death Eater "5" that has been carved into the wall.

The same wall, by the way, where Stiles keeps watching the mummy man write that thing over and over and over again — in chalk. Like what he used to write the code that told Barrow to axe-murder Kira. The bandaged face guy smirks at Stiles about how the bear trap used to be on his other foot and then starts shooting riddles at him like some kind of Band-Aid-covered Sphinx.

Hey, but guess what? Stiles is only sleepwalking. He sleepwalked himself right into that coyote den, which Agent McCall (very suspiciously) realizes when he reads the transcript of Stiles and Scott's phone conversation. Like, he goes, "Are these the exact words he said? 'It's cold and it smells real gross?' That's verbatim?" And the Beacon Hills desk cop is like, "Yeah, I guess?" And Agent McCall grabs Melissa, all, "To the coyote den, then!" In the car, they reminisce about when they were married and he was a dick.

In the dungeon, the mummy man tries to pull Stiles out of the bear trap. He thrashes and cries for help and fights him off. In the woods, Melissa pulls stiles out of the coyote den, while he thrashes and cries for help and fights her off. She says he was just dreaming, just dreaming, it's OK, you were sleepwalking, sweetheart. Stiles is not so sure.

School the next day is a somber affair. Lydia is feeling so crappy about leading the Get Along Gang to the wrong place and her banshee senses are hyper-stimulated so every single noise is thunder in her ears. Allison and Isaac visit Yukimura to ask him to translate these Japanese messages left on Allison's phone — which was turned off for some reason last night — and he tells them they're internment camp instructions, but for an internment camp that never existed. And Derek shows up to ask Kira to take him to the power plant and explain exactly what happened down there when Barrow tried to electrocute her to death.

At the power plant, Kira and Derek find a baseball bat and Derek immediately knows that it's Stiles' baseball bat (not a euphemism) and it is magnetized and drawn to some kind of jiggawatt box. Derek tells Kira to tell him every single thing she knows about being a foxfire. 'Cause, see, Aiden, who has no personal attachment to Stiles and can see this thing a little more clearly than these people who hold him so dear, kind of thinks maybe he's Nogitsune, the ultimate Death Eater. Derek refuses to entertain the idea at first, sputtering about how Stiles is such a small little dude and why would anyone want to use him/mess with his beautiful face? But the disappearing and the bat and the foxfire and goddammit.

Derek tells Scott that Barrow used the bat and the power plant to jump-start the demon inside of him, and also that when he talked to his dead mom in South America, she said the Hales used to be the protectors of Beacon Hills and maybe he and Scott can tag-team on those duties now. They'll be co-Buffys, OK? Scott agrees. But also he is so sad because Buffy isn't Buffy without Willow.

At the hospital, a lot of heartbreaking things happen. Stiles looks like he hasn't slept in a hundred years and before they stick him in an MRI tube to see if he's got the Brain Cloud like his mom had the Brain Cloud, he and Scott wrap each other up in the longest, tightest hug.

Scott promises that whatever is wrong with Stiles, he will fix it. I think he means the demon inside him thing and I also think he means that if it's a medical thing, he'll just give him the bite and fix him that way. The doctor rolls him into that MRI tube and the banging makes him crazy and the banging also makes Lydia crazy. She's sitting in her car hearing it but not reacting to it because she thinks she got something wrong and now she doesn't trust herself. And so she screams.

The neurosurgeon confirms to Sheriff and Melissa that their boy does have the Brain Cloud.

And in the MRI tube, Stiles wakes up to find himself face-to-face with the mummy man again. And the face that is face-to-face with his face is his own face. Because he is the mummy man. He is the Nogitsune. Guess who else knows that? Mrs. Yukimura! She's a Foxfire too! She comes to the hospital, summons some Death Eaters, says she'll kill Stiles to kill the Nogitsune. And Stiles goes, "Naughty little Oni. Why does it threaten us, Precious? Wicked, tricksy Foxfire. Oh, we hates it."

It had to be him, you know. It had to be Stiles with his One Face to Rule Them All. He is The Precious.

Next week: Melissa takes some time off from doing heart transplants to soundproof the walls in Scott and Isaac's bedroom, to give them a little privacy. Allison and Lydia have a pajama party that ends with them staying up all night listening to transmissions from number stations. Scott tries to help Stiles remember the Hobbit he used to be, but Stiles only takes it to mean he should paint the door of his coyote den green. And Derek breaks into Stiles' room in the night to watch him sleep. For research.