With only one episode of “Teen Wolf” Season 5 left before the midseason finale, the MTV drama had plenty of reveals. In episode 9, someone found out that Stiles (Dylan O’Brien) killed Donovan (Ashton Moio), Parrish (Ryan Kelley) discovered that his dreams weren’t just dreams, and Lydia’s mother (Susan Walters) revealed that she isn’t just a dumb human. But the drama doesn’t end there.

Scott’s (Tyler Posey) asthma is back in full force, and he isn’t the only one feeling off. He says that the whole school feels like they’re waiting for something bad to happen. It’s making the distance between him and his pack even worse. “Not talking makes it easier to keep secrets,” Scott says. The gang even spent most of the episode separated.

Malia Finds A Chimera: Malia (Shelley Hennig) sees a girl in class, Beth, nervously biting her nail until the whole nail comes off. She starts bleeding mercury, and Malia realizes she found another chimera. The werecoyote tries to go after her, but Mrs. Martin tries to stop her. She says Malia can’t help Beth.

“You know more than that,” Malia says as she shows her wolf eyes. Lydia’s mom isn’t at all thrown by the teenager’s glowing blue eyes.

“I think you should focus on school, all of you,” Lydia’s mother says.

Malia leaves class anyway, but she can’t save Beth. She sees a Dread Doctor snap Beth's neck. She tells Stiles that she can’t handle all of these dead bodies anymore. It’s too much.

What is Parrish? Stiles, meanwhile, is with Lydia (Holland Roden). They’d been searching for the nematon in the woods for days, but the supernatural place is hard to find.

Lydia wants to talk to Parrish, but Stiles worries about Lydia discovering that he killed Donovan. He tries to make up a reason that they can’t go to Parrish, but nothing he says is good enough for Lydia. She can’t use her banshee powers to locate the bodies, so she goes to the deputy.

Later, Stiles calls Lydia about the latest dead chimeras and says not to get in Parrish’s way. Of course, Lydia is intentionally getting in his way. The banshee tries to get Parrish to stop thinking. After all, that’s how she activated his powers around fire earlier this season. She starts fighting him and eventually his eyes change. He suddenly finds the nematon and all the dead bodies.

Parrish wants to turn himself in, but Lydia thinks he might be protecting the supernatural. “Maybe you’re keeping the secret safe. Maybe that’s what you do,” Lydia reasons.

Parrish reveals that his dreams didn’t just include the chimeras. His dreams included hundreds of dead bodies. With that revelation, the deputy locks himself in jail. The Sheriff wants him out, but Parrish knows he can’t be trusted when there are two chimera bodies out there.

Stilinski’s Search: Stilinski (Linden Ashby) is on a mission to find the chimeras, and he wants to finally make some progress. The Sheriff decides that he wants to look for the failed chimeras that are being targeted. The deputies can use a black light to determine if any of the chimeras have started bleeding mercury.

Stilinski takes his black light into the library and finds mercury right away. He knows that only Stiles and Theo’s (Cody Christian) key cards were used to get into the library one night, and he thinks about how Stiles was sure that Theo was a bad guy. The Sheriff doesn’t seem to suspect that Stiles killed a chimera.

Stilinski confronts Theo, and Theo claims that he killed Donovan. He says that it was him who climbed the scaffolding and accidentally killed his classmate. He breaks down in tears and the Sheriff gives him a hug. It would seem like a sweet gesture if he hadn’t told Scott a very different story.

Scott Tries to Protect the Chimeras: Scott apologizes to Theo. He thinks he is a disappointment as an Alpha, but Theo assures him that he’ll stand by Scott through anything. Theo seems desperate to be part of the pack, and he makes it clear how far he is willing to go when he angers the Dread Doctors. He yells that he needs Hayden (Victoria Moroles) alive, but the Doctors don’t want to save a failed experiment.

Unfortunately, Hayden is definitely a failed experiment. After a sweet kiss with Liam (Dylan Sprayberry), the silver liquid starts coming out of her nose. “Don’t tell anyone,” she says. “You can’t tell anyone.”

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Corey (Michael Johnston) seems to be doing better, at least for a little while. Mason (Khylin Rhamo) tests his limits with weights, and the small chimera lifts hundreds of pounds. The fun couldn’t last for long, though. Corey starts vomiting mercury a little while later. He is at school when it happens, so he is sent off in an ambulance.

As Theo and Scott drive to the hospital, Scott wants Theo to talk to him, and Theo reveals that Stiles killed Donovan. Theo told Stiles earlier that they should both own up to killing chimeras, but Stiles had a vision of himself impaled. It looks like Theo made the choice for him, but the new wolf twists the truth once again. He doesn’t mention that he also killed a chimera, and he makes it sound like Stiles intentionally killed Donovan.

“I only saw the end of it and when I saw what Stiles was doing, I couldn’t stop him,” Theo says. He claims that Stiles just kept bashing Donovan’s head in with the wrench. “I kept telling myself it was self defense but, Scott, I’m sorry. I’ve never seen anything like it, and I’ve never seen anyone that angry.”

Scott and Theo get to the hospital and see everyone in disarray. They realize that it wasn’t the Dread Doctors who attacked people in the emergency room. It was Corey, who they don’t realize has gained the power of invisibility.

They see the elevator doors faltering and realize that the Doctors have arrived. They have to find Corey as soon as possible if they want to save him. The chimera goes invisible to hide from the villains in plain sight, but it seems the bad guys can still see him. A Doctor stabs him with a sword immediately.

Knowing that the Dread Doctors are coming for his girlfriend, Liam decides to runaway with Hayden. “What if I turn out like Tracey? What if I hurt you?” Hayden asks.

“I’ll get over it,” Liam says.

However, they don’t get the opportunity to ditch town. The Dread Doctors show up at Sinema as Hayden grabs her last paycheck. The villains knock Liam down, but luckily, Scott shows up. He attacks the Doctors, who don’t react much to the Alpha’s assault. Theo even joins the fight against the enemy, but they can’t save Hayden. The doctors give her a shot in her neck and then leave her. However, she doesn’t die.

“I need more time,” Theo tells the Doctor that has him by the throat. The Doctor throws Liam to the ground and leaves.

The wolves are pretty sure that Hayden was given a shot of mercury, but they aren’t positive what that will do. The shot could be destroying Hayden from the inside. Liam questions if she’ll heal, but Theo explains that the chimeras are basically knockoff werewolves. They don’t always work as well as the real deal. Liam suggests turning her into a real werewolf, but only Scott can do that. The Alpha refuses to bite her.

Scott Confronts Stiles: In a dramatic conversation in the rain, Scott shows Stiles the wrench he used to fight off Donovan. Scott asks why he didn’t tell him. “He was going to kill my dad. Was I supposed to just let him?” Stiles asks.

“You weren’t supposed to do this,” Scott says. “None of us are.”

Stiles yells at him, but Scott questions if it was self defense. The Alpha wants to believe his best friend. “Stiles, we can’t kill people that we’re trying to save.”

“Say you believe me,” Stiles demands.

“We can’t kill people. I believe that,” Scott says

Stiles asks how to fix the situation, but Scott can’t give him an answer. Scott tells Stiles not to worry about Lydia or Malia. He recommends that Stiles talk to his father and then he leaves Stiles alone in the rain. He doesn’t realize that Theo was listening to their whole conversation.

"Teen Wolf" airs Mondays at 10 p.m. EDT on MTV.