Everyone got a blast from the past in “Teen Wolf” Season 5, episode 6. Dr. Valack (Steven Brand) told the pack in last week’s episode to read his book in order to access any hidden memories they might have of the Dread Doctors. They followed his advice, but it just led them to even more trouble.

Episode 6 starts with a flash forward to the end of the episode. Scott (Tyler Posey) reaches for his inhaler, but one of the Dread Doctors steps on it. Malia (Shelley Hennig) distracts the villain while Melissa (Melissa Ponzio) helps her son. Malia runs to the elevator and they escape the Dread Doctor in the knick of time.

Then, the episode flashes back to before everyone read the book. The police find more human-sized holes on the sports fields. The Sheriff (Linden Ashby) realizes that Donovan (Ashton Moio) is likely a chimera, so he adds him to the list. Still, they're now looking for at least 7 or 8 more chimeras. Stiles (Dylan O’Brien) doesn’t say that he killed Donovan, but he notes that the teenagers had to have something in common to draw the Doctors to them.

Meanwhile, Lydia (Holland Roden) has Parrish (Ryan Kelley) teach her how to fight. She ends up in his arms, and it looks romantic for a second. However, a sudden memory of the Dread Doctors ruins the moment.

At school, Scott asks Theo (Cody Christian) to watch out for any strange behavior from other students, but they realize that they don’t have much to go on. They don’t know how to identify a chimera yet. That’s why they have to read Valack’s book, even though Theo tries to discourage him. Theo says that if he can’t convince Scott otherwise, then he’ll read the book too. Everyone grabs a copy, except Malia, who already read it.

While the group reads, Stiles and Malia lie to each other. Stiles says his shoulder injury is from the hood of his Jeep falling, not Donovan. Malia claims that her vision only included the accident, not the Desert Wolf. Eventually, the whole pack passes out, except Theo. He watches Kira (Arden Cho) speak Japanese in her sleep and records her.

They wake up without any hallucinations and head back to school. While in class, Lydia and Theo notice a classmate whose hair is falling out. Lydia goes after her and discovers that the girl has been dealing with stress-related hair loss for years. Lydia looks and the bald spot and it abruptly changes into an open wound before her eyes. Suddenly, Lydia is on the floor. The hallucinations from Valack’s book are finally kicking in.

Lydia is in a bathroom at Eichen House. Her grandmother has the injury that she visualized on her classmate. “They’re coming Lydia,” her grandmother, who was also a banshee, said. “They’re coming for all of us.”

Lydia realizes that she didn’t get the right memory in her hallucination. Her grandma had nothing to do with the Dread Doctors (at least as far as she knows). The banshee realizes that those flashes of the Doctors appearing during her surgery might not be her own memories.

Kira’s didn't have any flashbacks at all, her own or otherwise. Her lack of hallucinations were explained by Mason (Khylin Rhambo). Liam's best friend has done research on kitsunes and learned that they have trouble with language. Since the whole book is basically a language trick that affects the memory, Kira’s powers won’t let her process it.

Scott isn’t as lucky. The alpha tries to hand in the drop form for his AP biology class when he starts having difficulty breathing. He has visions of dogs and realizes he is having an asthma attack, something he hasn’t had to deal with since becoming a werewolf. Scott recalls being in the hospital as a kid while having an attack. Liam (Dylan Sprayberry) saves Scott with an inhaler and an intense stare with his wolf eyes.

Malia also doesn’t have any revelations about the Doctors, but she is hoping that Theo won’t tell anyone that she saw the Desert Wolf. She confronts him in the gym, where he is conveniently shirtless and flexing, and warns him that she won’t owe him anything. Theo simply told her that he wanted to be in the pack and she could say something to Scott.

Theo is determined to work his way into the pack, but it’s clear that he is trying to cause trouble too. He tells Scott that he translated what Kira has been saying in Japanese in her sleep. It means, “I am the messenger of death.” Scott admits that with her new kitsune aura and powers developing, he isn’t sure he can trust his girlfriend.

At the hospital, Lydia and Stiles check out the room where Lydia had her surgery. While Stiles goes to get someone to fix the lights, Lydia listens to a machine say “Hayden.” She sees someone in surgery with the Doctors. His torso is blue and glowing when they cut him open.

While Stiles is finding maintenance, he starts to hallucinate. He sees his mother. He follows her down the hallway. He sees his mother say that someone is trying to kill her on the roof of the hospital. The Sheriff talks her down from her delusion. Stiles realizes that she is talking about him. She believes her 10-year-old son is trying to kill her and then she attacks him. Suddenly, she morphs into a chimera.

Theo and Scott find wires in the school basement that were clearly ripped out intentionally. When they discover that Lydia and Stiles are facing similar electrical problems at the hospital, they realize a new chimera is messing with the power.

They go to the hospital and Theo fights off Stiles’ attacker, but Scott is attacked by one of the Dread Doctors as he suffers from an asthma attack, bringing viewers to the opening scene where Malia fights off the Doctor and they escape into the elevator without a second to spare. While they fight one of the Doctors, Theo literally rips the chimera’s throat out to save Stiles.

“You can’t say anything,” Theo begs. “Please don’t say anything.”

“Why not?” Stiles asks.

“Because I never said anything about Donovan,” Theo says. It looks like the new villain knows that Stiles’ killed the chimera.

Elsewhere throughout the episode, Liam’s story with Hayden (Victoria Moroles) evolved. Liam was determined to pay back Hayden for the drinks that he knocked over, but Hayden didn’t really want his help. Then the two got competitive in gym class, which resulted in Liam accidentally using his werewolf powers to make a goal.

Mason explained Liam and Hayden’s past. Hayden walked into a fight between Liam and another guy in sixth grade. He gave her two black eyes for the week of yearbook photos. She returned the favor, but she still holds a grudge.

Liam went back to the club to try and give her money again after he heard her sister say that Hayden is on expensive medication. Hayden reveals that she had a kidney transplant a couple years ago and that’s why she has the pills. She is working at the club to help her sister pay for the medicine that costs $200 a bottle. Liam realizes that this makes her special. He holds a glow stick up to her eyes and sees them glow in a way that’s not human. It looks like Hayden might be a chimera.

“Teen Wolf” Season 5 airs Mondays at 10 p.m. EDT on MTV.