At the vet’s office, Deaton gives a dog a shot as Scott helps the dog get ready. The dog’s owner tries to get the dog in the car, but he’s skittish and runs off. In the stool sample Scott finds mistletoe, poisonous to both dogs and werewolves. The dog’s owner walks down the alley that the dog ran into. He sees his dog under a trash container, but when he reaches for the dog something bites him. When he looks up the dog is actually across the alley, and he reaches out to find out what it was under the container right before the screen cuts to black. The little dog, Bullet, runs into Scott’s arms and his owner is gone.
Ms. Blake walks into school and thinks she’s heard something strange, but she sees nothing. She feels reassured once she enters her classroom until she turns and sees Derek waiting for her. She picks up a wooden rod, holding it in front of her in self-defense, and Derek asks her if she’s okay. She responds with “Physically or emotionally?” before adding “Though, I guess that presupposes I was emotionally okay before any of this and according to my therapist that’s been debatable for a long time,” eliciting something along the lines of a smile from Derek. He takes the rod from her and they talk for a moment longer. She promises not to talk about what happened before asking his name. She introduces herself as Jennifer.
Scott tells Stiles about the guy at the vet in the locker room before cross country practice and Stiles tries to find out if he’s virgin before deciding that “someone needs to sex me right now!” Danny offers and Scott and Stiles exchange an alarmed look before Danny tells them that he’s kidding. Isaac walks in, late. Apparently cross country is required for lacrosse players to keep them in shape during the off season.
The Alpha twins approach Isaac during practice and Scott tries to reason with him, but Isaac refuses to listen. Isaac seems to lose them on the trail before he’s suddenly attacked and shoved down a shallow hill. Scott intervenes before they can actually hurt him, and all four wolves have partially shifted before they hear a scream and find the guy from the vet, killed like the others. The Sheriff appears at the scene with other deputies and tries to get the kids off the crime scene. A girl comes, screaming and crying for the boy, who was apparently named Kyle. The twins seemed confused by the murder, and Stiles tries to point this out, but Isaac isn’t convinced. Both try to get Scott on their side, and Isaac vows to kill them.
Cora Hale works out in the loft with Derek watching. She’s struggling, and Derek tells her to stop because she’s not done healing, but Cora wants to fight back as soon as possible. Derek kicks her hand out from under her while she’s doing push ups, and Cora is furious saying, “I came back for this? I can't believe I got my ass locked up in a vault for three months for you.” Derek tells her he’s sorry to disappoint her before the proximity alarm goes off and the alphas, minus the twins, appear. Cora immediately goes into fight mode, but she’s not at full strength yet, and the former Nurse from the hospital immediately delivers a blow that would have been lethal to a human by throwing her to the ground where her head slams against Derek’s concrete flooring. The female Alpha pulls a pipe from the loft’s exposed industrial system and fights Derek with it before putting it through his torso.
Ms. Morell is doing phonetique with her French class when she notices Allison sleeping in the back. Allison does not wake until she hears her mom’s voice, and Morell asks her if she’s tired in French. Her class laughs at her and Allison apologizes. Morell stops to talk to Allison and suggests that maybe they should talk in guidance. Allison changes the subject to what happened at the bank. Morell tells Allison that she won’t give her lunch detention if she can name the French word that’s also used in English that could describe their situation. Allison doesn’t know, and Morell tells her that the word is impasse.
In Mr. Harris’s physics class, Scott tries to convince Isaac to just wait before he tries anything with the twins. Isaac excuses himself to the bathroom, and Scott tries to follow, but Harris won’t let him. Out in the hallway Isaac sees the twins. One punches the other and Isaac stops in confusion. Isaac watches as one twin completely beats the crap out of the other before swinging him at Isaac’s feet and walking away. Isaac, essentially framed, receives detention.
At the loft, Deucalion tries to talk to Derek as the female alpha, Kali, twists the pipe through his back. The other alpha lets Cora up, but she knows better than to try to rush to him at this point.
Scott tries to keep Isaac from getting upset before noticing one of the twins, Aiden trying to cosy up to Lydia. Scott’s inevitably pissed, and Isaac is slightly amused.
At the principal’s office the Sheriff is talking to the girl who had cried out for Kyle, the boy who was killed. Stiles is watching from the window, but ducks down when he realizes the conversation is ending. Stiles tells the girl, Ashley, he’s about to ask a horribly insensitive question and apologizes in advance before asking her if her now dead boyfriend was a virgin. She slaps him but does answer the question. He wasn’t a virgin. The Sheriff overhears her answer as she is walked away by another deputy and yells at Stiles, who doesn’t put much effort into defending himself.
Back at the loft, Kali continues twisting the pipe in Derek’s back. Blood is dripping from Derek’s mouth. Deucalion wants Derek to kill one of the members of his pack.
In detention, Isaac and Allison are told to restock the janitor’s closet together. Isaac is uncomfortable with this, probably since they haven’t interacted since the whole showdown in the spring where they were trying to kill each other.
Boyd has returned to the school and has a brief conversation with Stiles. Isaac and Allison enter the closet and Isaac is immediately set on edge by the small space. Allison asks Isaac if he told anyone that he saw her at the school. It seems as if Allison is apologizing for what happened before the door shuts and Isaac begins to panic. The vending machine has been placed against the door so even Isaac can’t get it open. He begins to pound on the door anyway, having flashbacks to the freezer. He eventually shifts and attacks Allison before Scott gets them out and gets Isaac under control. Allison’s right wrist has been cut up, but otherwise she’s okay. Isaac apologizes profusely although neither Scott nor Allison blame him.
Stiles is discussing human sacrifices with Lydia. He reveals that he’s just talking because Scott’s off to fight the twins, Ethan and Aiden. Apparently Lydia didn’t realize that they were alphas until that point, but she doesn’t tell Stiles that. Stiles has decided that the murders are in groups of threes, three virgins, and then three of something else, maybe three people who own little dogs. Lydia tells him that it’s probably not his job to figure this one out.
Allison is hot-wiring one of the twin’s motorcycles with Isaac watching. Allison gives him a very quick tutorial on how to operate the bike before taking a picture and sending it to Scott. In Ms. Blake’s class, Scott begins to take parts of the bikes that they have removed out of his backpack and puts them on the desk. All three Werewolf hear an engine rev, and Aiden runs out of the classroom. Isaac rides the bike through the hallway. Aiden yells at him to get off the bike, and Isaac flips over Aiden, walking away just as the entire class walks into the hallway and sees Aiden with his bike, keys in the engine. Ms. Blake walks out and tells Aiden he’s going to end up suspended.
Stiles visits the animal clinic during his free period thinking Deaton could have information about the murders.
At the loft Derek’s condition is beginning to visibly worsen as Deucalion continues his discussion of the alpha pack. Cora is beginning to look very worried. Deucalion shares that when an alpha kills one of their betas they absorb the beta’s power. Apparently Deucalion found this out accidentally, but ended up killing all his betas once he realized. Deucalion remarks that Derek looks like his mom before beginning a rant that he is the “Alpha of Alphas”, the “Apex of Apexes”, the “Predator of Predators”, “Death, Destroyer of Worlds”, and “The Demon Wolf,” complemented by dramatic lightning although there is no evidence of a storm happening. As his rant culminates Deucalion’s sunglasses shatter. Kali pulls the pole out of Derek’s back, and the alphas leave as Cora rushes over to her brother.
Lydia is completing a detailed drawing of a tree when Danny walks up to her. Apparently Lydia is sitting in the middle of the band room although she’s not part of the music program. The students leave because apparently fifteen minutes have passed and their teacher still hasn’t arrived. Lydia notices a phone sitting on the piano in the front of the classroom making noise, and she scrolls to the front of the recording. It’s the band teacher playing the piano. She continues scrolling until she sees a spike in volume on the visualizer. Something hits the piano loudly and the audio stops briefly before a chanting is heard. Lydia turns up the volume to hear it better before becoming unnerved.
At the clinic, Stiles is explaining what he’s found in regards to the druids and human sacrifices. Stiles realizes that Deaton is aware of everything he’s saying already, and Deaton admits that he’s been denying what’s going on because he’s spent a good ten years trying to avoid this. Apparently the murders are somebody copying an old druid ritual.
Stiles's phone rings, and it’s Lydia telling him about how the band teacher has been taken. There’s a bloody handprint on the piano. Stiles and Deaton go to the school to check out what Lydia found, and Stiles thinks that the next group is soldiers because Kyle was in ROTC and the band teacher was a former military officer. Stiles goes to call Boyd when Lydia remembers that Mr. Harris was also former military. The same chanting heard on the phone is heard in Harris’s classroom.
Isaac and Scott are walking through the hall after school when the twins appear. They strip off their shirts, leaving Scott and Isaac confused, before combining into the larger alpha. Isaac’s ready to fight, but Scott pulls him away. They don’t make it far before getting caught, but Deucalion appears and the twins separate, knowing that they've been caught. Deucalion slices them both on the cheek with the blade in his cane before leaving. The twins follow him.
Deaton, Lydia, and Stiles enter Harris’s classroom. He’s gone, but all of his stuff is still in the room. Tests graded as “R” and “H” are found, and Deaton puts them together to spell “darach”, the name for a druid who’s turned to the dark side.
At the loft it is now raining, and Derek is staring out the window. Apparently he’s told Isaac that he needs to leave. Isaac tries to figure out if something happened that he missed, but Derek refuses to tell him anything, just that it’s “too much” to have both him and Cora there in the loft and that he needs to be out before the morning. Isaac doesn’t know where to go, and when he keeps pushing Derek throws his empty water glass at him. Muscle memory serves Isaac well and he ducks and covers well before the glass shatters, but that’s enough to get him out of the loft. Cora is seen hiding just around the corner and listening to the conversation, looking stressed.
Scott is working at his desk when he hears a knock and Isaac enters, soaking wet and asking for a favor.
Harris is tied to a tree in the storm, pleading. Apparently he was in contact with whoever is committing the murders because he says that he’s done everything that the murderer has asked. The garrote tightens around his neck and he is strangled.