The episode opens with kids smashing a pumpkin, showing that it's Halloween. The kids see a pack of figures (which we will refer to as "Oni") approaching them.

We cut to Isaac on the floor of the Argents' house, breathing heavily as Allison and Chris finally break through the door and get to him. Isaac is cold to the touch and barely responsive, as Chris slaps him and tries to trigger him to turn into his werewolf self.

Eventually after Chris's slaps and calls, Isaac turns, and describes to Allison and Chris that there were five figures in all black with covered faces and eyes that glowed like fireflies. He says they came out of the shadows, and Chris admits he doesn't know what that means before making the teens promise to keep it quiet for 24 hours.

Allison points out that whatever those things were, they could have killed Isaac, but Chris insists that they didn't because they were after him instead. He goes to his room and pulls out a box, pulling out an Oni mask that has been split in half.

—

Cue credits.

—

We see everyone sitting in the sheriff's office as agent McCall asks them all if they arrived at the same time to the scene by coincidence. The boys are confused, arguing lightly about who the agent is talking to, Lydia butting in "I think he's asking all three of you."

"Let me ask the questions, just so I have this absolutely clear," the agent says as the boys nod.
Agent McCall recaps the whole story, and asks how they knew Barrow would be at the power substation.

Stiles answers that it was because he was an electrical engineer, so 'where else' would he take her.

"That's one hell of a deduction there, Stiles," McCall says with a small look, Stiles assuring him that he's "just like his pops."

"We made a good guess. We got lucky. That's all," Noel clears up, trying to take control of the situation. McCall asks where Scott and Kira were, and they have a little fumble before settling on "We were eating sushi & pizza."

McCall asks the sheriff if he believes any of this, and the sheriff confirms that he thinks they were all just in the right place at the right time and Kira is lucky for it.

McCall asks Kira if that's how she remembers it, and after looks from the others, she confirms and asks for her phone back. McCall denies her this and the teens all leave, Scott being held back to have a word with his father.

—

Back home, Kira lights a candle and tries to check her newfound powers by taking a photo and seeing the outline of a fox around her.

—

After the break, we're back at school, where the coach is saying that just because there's no power doesn't mean there's no school. Stiles points out that that's a triple negative from where he stands at his locker, Noel beside him taking out some of his own books before putting in his earbuds.

Stiles drops a set of keys and wonders aloud where they came from as Noel's head bobs to his music, and Scott enters the school and freezes upon seeing Kira.

As Kira turns heel and starts walking away, Scott rushes to follow, but Stiles stops him. Noel removes one of his earbuds and the three boys argue whether or not Scott should talk to her. Stiles reasons that until they know she isn't a threat, they should all steer clear, to be careful.

"But what if she's like me?" Scott asks, and Noel says "We can't walk through that much electricity unscathed, Scott. She might be something, but she's definitely not like us."

—

After Danny and Ethan discuss the blacklight party, Aiden asks his brother why he wants to help Danny.

Ethan suggests that Aiden try acting like a human to get into Scott's pack, and then Aiden and Lydia have a discussion about Aiden being a bad guy.

Aiden, reluctantly, turns around in his seat, and tells Danny "I may know a guy who may know a place where you may be able to have your party,"

We then see Derek leaving the loft, implications heavy.

—

Scott and Kira have a discussion about the previous night, and Kira lets Scott see her Kitsune side before they talk about needing to get Kira's phone back.

Derek then has a scene where he gives trick-or-treaters candy and gives them a good scare, before Oni show up all around him and we cut to black.

—

"Why should I do this for you? I think I've made it abundantly clear how I feel about recent events concerning you and my pack," Noel says under his breath after the break, glaring daggers at Aiden with his hands shoved deep in the pockets of his leather jacket.

Aiden gives a soft sigh, saying "This is me trying to change. I'm making an effort, and I'm trying to fix those mistakes I made."

"That was the furthest thing from a mistake I've ever seen," Noel says through his teeth with a shake of his head, turning to walk away but finding himself looking right at Danny, who stands beside Ethan.

"Noel. Come on. You're the only one with keys to this place and it's perfect," Danny says, followed by "What did the twins do that has you so mad in the first place?"

Noel sets his jaw and creases his eyebrows, knowing that spilling the supernatural secret will only make things worse for them all. Thinking quickly, he says "Typical stuff that I deal with. Name calling, too rough checking me in lacrosse, shoving me into lockers; Quintessential bully behavior."

"We want to make amends," Aiden emphasizes, touching Noel's upper arm almost pleadingly. Noel jerks his shoulder away and glares, looking back at Danny, whose expression is hopeful. Unable to say no to his friend, Noel gives a resigned sigh.

"If I do this for you... You keep it to yourselves. You don't tell Scott, and you don't see it as forgiveness, and you don't dare tell Derek, wherever he might be. I'll be shocked if he didn't change the locks months ago, so if he did like I'm sure he would, you find your own way in," Noel says, pulling out his ring of keys and holding one tightly.

Aiden nods profusely, as Noel goes up to the door of Derek's loft and sticks the key in the lock. He seems half surprised when it still works, as his eyebrows knit together in thought and he slides the door open.

His breath catches as he looks around the space, breathing in deeply and looking toward the couch as his eyes flutter closed and we go back to the season 3a finale.

—

In an extension of canon scenes, we find Noel waking up on the couch after the ritual he and Derek performed to expel Laura from Noel's body and sacrifice Derek's alpha status.

As soon as Noel's eyes open, Derek's widen slightly, as he leans in and presses a kiss to Noel's temple.

"Derek?" Noel asks weakly, as Derek answers immediately "Hey, yeah, it's me, I'm right here."

"Did we...?" Noel asks weakly, unable to finish a thought as his eyes flash gold and fizzle out to green. Derek nods, kissing his temple again as he says "We did it. Cora's fine, we did it. I couldn't have done it without you."

Noel smiles, opening his eyes fully and raising a weak hand up to Derek's face. He strokes a thumb over the former alpha's facial hair, and without thinking, the two share a long and slow kiss.

—

Back to present day, Noel flinches, looking away from the couch to the twins and holding up his key to Derek's loft.

"This? It never leaves my hand. And blame never finds its way back to me. Am I understood?"

"Loud and clear," Ethan confirms, as he hits a black light and gets Danny's resounding approval of the space.

—

After Kira and Scott's mission to delete the photos off of Kira's phone, we're at the loft, at the black light party.

—

Noel, presumably playing dumb and innocent, walks up to the door with Allison and Isaac, eyes wide in shock at the amount of people Danny managed to squeeze in.

As his body is painted, Oni surround Danny unnoticed, and Ethan goes to get ice from a back room of the loft. He fiddles with the light and finds himself surrounded by Oni as well, before we cut to black.

—

As people dance, Stiles tells Scott about the key he found, and Scott asks if they should leave and figure it out.

After a girl (Caitlin, from season 3a) kisses his cheek, he says it can wait, as he follows her and calls out a lie of "I'm gonna, uh... Go find Noel. If I had to guess, he's in Derek's bedroom, sobbing. I'll make sure he's okay, y'know, give him a hug or something. He's a touchy feely kind of guy."

Not believing his plan for a second, Scott responds "Go, I'll find him!" with a fond smile as he looks to Kira and holds her hand.

Scott looks around the crowd and smiles brightly when he sees Noel across the room, about to drag Kira over to him when he realizes that Noel's talking to Allison.

The two laugh at a joke Noel made as Allison turns and looks in Scott's direction, and her smile fades upon seeing Scott with Kira. Knowing who Allison is, Kira slips away as Scott and Allison make eye contact.

The two share a look and Noel gently leads Allison away by the elbow, with a passing look of apology to Scott. Scott returns the smile in a way that says 'it's okay' as he scans the crowd to find Kira once again.

—

Stiles and Caitlin share a scene, as well as Aiden and Lydia, before we cut to Noel and Allison in a dark part of the loft. We can still hear music, but lighting is sparse, as Allison says "I knew he would show up, I shouldn't have come."

"You came to have fun, he doesn't have to ruin that fun for you," Noel assures her, adding "He obviously doesn't want to, either, or else he would have come right up to us. You left him alone with Kira, he left you alone with me, he's respecting a boundary."

Allison looks up at him and sighs, letting her head fall with a nod of resignation. "You're right. Why are you always right?"

"Hidden talent," Noel jokes and wraps one arm around her, pulling her into a loose hug as she tucks her hair behind her ear.

"Are you really okay to be alone back here?" Allison asks him as they part from their hug, Noel nodding and heaving a short sigh. "Yeah, I'm fine. I really didn't need an escort to the bathroom."

"I just know the place still smells like him, and I didn't want you to get too overwhelmed and be alone," Allison reasons, patting his chest with a hand and saying "Fine. I'll go find Isaac. Find us when you're done, okay?"

"Of course," he says and waves as she walks away, going a little ways further down the hall and seeing the overwhelming line at the bathroom.

He sighs and closes his eyes in annoyance, bouncing a few times before turning around and going up to another closed door. He reaches for the handle, hesitating, before opening it and stepping inside.

We see a bed, and a television, seemingly untouched and unused for a while. Noel breathes in deeply for a beat and starts to walk across Derek's bedroom toward his bathroom, but before he can make it, an Oni appears in front of the door and another snaps into existence behind Noel.

He looks at them both in shock and fear, and we cut away from him and see Isaac and Allison discuss their relationship before having their bodies painted.

—

Lydia begins to see the Oni in the room all around her, calling out for Scott as she finds a place where she can be alone (Derek's balcony).

She hears a strange clicking sound, as Oni rise up from the ground at her feet and she tries to scream. The Oni silences her and stares at her with piercing yellow eyes, as we cut back to the party and then to commercial.

—

Caitlin and Stiles share a few kisses, and Stiles realizes the origin of the key after Caitlin points out that certain chemicals can make objects glow under blacklight. He apologizes to Caitlin, brings her a bottle of water, and after Scott and Kira share a kiss as well as Isaac and Allison, Allison notices something behind Isaac's ear.

Instead of dragging Isaac to the bathroom and finding Ethan, she drags him to Derek's bedroom, and after seeing the inverted number 5 behind Isaac's ear, they see Noel curled up and shaking on the floor.

Danny and Aiden find and grab Lydia, pulling her inside and to a heating vent, as Isaac sits Noel up against the wall and shakes him vigorously.

When Noel remains unresponsive, Isaac grabs his arm in both hands, and Allison asks fearfully what he's doing.

"It'll trigger the healing process," Isaac says, wincing and adding "Or if it doesn't, I'm sure whatever noise he makes will at least get Derek's attention."

Then without warning, Isaac wrenches both his hands and snaps Noel's arm clear across the forearm. Noel's eyes blaze gold as he howls in pain, and Lydia begins to warm up as Aiden finds a 5 behind her ear and Allison discovers one on Noel as well.

She points out how it's exactly the same as the one Isaac has, and we see Derek reveal that he has the same 5 behind his ear.

We hear Noel's howl above it all as we watch Derek, whose head snaps up and he unleashes a responding roar that Scott immediately recognizes.

—

We watch as Derek approaches the DJ booth, and after handling the bouncer, he flips the DJ's table and looks around the party distastefully. Once all eyes are on him, Derek scans the crowd again, before yelling firmly for everyone to get out.

As everyone runs out, Oni watch the crowd, and Lydia insists they have to find Scott. Isaac and Allison run in, with Noel in their arms and Ethan behind them looking incredibly weak.

All the Oni turn to face Aiden, as they approach him one step at a time and Derek and Scott move in to attack them. Derek manages to snap one of their necks, but they immediately heal, throwing Derek like a rag doll as Noel calls out his name and tries to get out of Isaac and Allison's arms to get to him.

They keep him back, Isaac launching in to try and do his part, but the Oni he stands before pulls a sword from its chest and he concedes without argument.

Allison begs someone to do something, as we see Aiden get branded before the Oni turn on Scott.

Suddenly, the sun rises, and they fade to dust as Scott asks what the hell those things were. Derek doesn't say anything, but the camera goes to him as he looks over toward Noel, who looks absolutely exhausted.

Isaac tells Allison her dad's 24-hours are up, as we see Chris struggle in his home before collapsing.

—

Stiles, at the school, uses his new key to try and open a door, looking inside as we hear agent McCall refresh our memories on how Barrow knew to go after Kira (someone broke into the chemistry lab and left him the note).

Stiles approaches the board and writes the same numbers beside the other spelling of Kira's name, and finds that they look completely identical.

—

The episode ends.