As Hellhound Parrish advances down the hall, Theo grabs Lydia and places his claws to her throat. He draws blood and warns Parrish to back off. The deputy continues to advance. Theo presses his chimaera pack to take him. They are reluctant but Tracey steps up, growls and takes a run at him. She stabs her claws into his stomach but he doesn't seem to notice, batting her away with little effort. Josh rips away one of the electrical conduits running the length of the hall and grabs the exposed wires inside. He sends a full charge into the hellhound but is also ineffective. Parrish shoves him into the wall.

While Theo is distracted, Valack plunges his trephination drill into the back of the chimaera's leg. Theo drops Lydia and Valack pops him in the face with the drill's handle. He takes Lydia.

Parrish is beating on Josh when Corey becomes visible and grabs his arm. Parrish's body ignites and Corey is consumed in a ball of flames.

Stiles steps in front of Valack and Lydia to block them but Parrish throws a now flaming Corey, knocking Stiles back and allowing Valack a chance to get by.

As Parrish continues his advance, Theo picks up the piece of electrical conduit pipe and hurls it into the Hellhound's chest. Parrish's fire subsides and his eyes return to normal as he sinks to the floor.

Stiles manages to roll Corey off and starts to pursue Valack and Lydia but is stopped by a locked door.

~~~

In a flashback, Liam and Hayden make love. In the afterglow, he asks her to join Scott and Selene's pack against Theo. He says he knows Theo wants to steal the Beast's power. He says it won't work that the beast will simply rip his head off. She asks if Scott can do better and Liam says he thinks he can because he's different since he died and came back. He asks her what she would want him to do if she died again.

~~~

Hayden is still guarding Deucalion in the underground lair. He asks if she is questioning her loyalties. He wonders why Theo didn't take her since she's faster and stronger than some in the pack. She says she knows she is a liability because of her feelings for Liam. He tries to get her to leave but she is reluctant. He tells her that he's no friend of Theo's and that she should worry less about being a liability and more about her ability to lie.

~~~

Liam, Selene, Brett and Scott are still outside the closed unit, where they overpowered the guards. Scott picks up one of the guard's two-way radios and pushes the button as he pretends to be a guard himself.

"Does anyone have eyes on the Closed Unit? I need a status report" Scott states and Selene raises an eyebrow.

"It's a war-zone down here" A guard responds over the radio. Scott and Liam exchange worried looks before Scott nervously replies.

"Uh, 10-4. And what about the patients? Lydia Martin?" Scott asks and Selene hits him across the head. The guard with whom Scott is speaking suddenly becomes suspicious, much to the boys' horror.

"Who is this?" The guard asks.

"It's... Unit 9" Scott says anxiously. There is a long pause before the guard responds.

"There is no Unit 9.-" Before the voice can continue Selene takes the radio and crushes it

"All right, we need to figure out another way to get into this closed unit," Selene says and looks at the open gate.

"How do we get through the mountain ash?" Brett asks.

"I don't know ... But there's somebody else here that might be able to help us" Scott says. He looks at Selene who nods.

"Go find Meredith. I got something else I want to try" Selene explains and Scott nods. He and Liam leave while Brett turns to Selene.

"Why do I feel like this is a stupid idea that can get you killed"

"'Cause it probably is" Selene admits.

~~~

Stiles is still trying to get through the locked door in pursuit of Valack and Lydia. Theo kicks in the door and tells Stiles he won't find her without him.

~~~

An Eichen guard finds the broken piece of electrical conduit lying on the floor. Tracy stabs him in the back with her claws. She takes his radio and runs off back down the hall.

~~~

Malia and Kira are still trapped in the morgue. Lightning crackles around Kira's body and connects with metal objects in the room. Malia suggests grounding her with something but neither one knows how. Kira says she should have stayed with the Skinwalkers because she'll never be able to control her abilities. Malia points out that it worked earlier and she was able to cause the brownout. Kira's eyes flash orange and she shouts for Malia to go.

~~~

Natalie is trapped outside Eichen House. The gate is locked and electrified. She picks up one of the downed guard's taser stick and looks determined.

~~~

Scott and Liam find Meredith but she is unresponsive.

~~~

Theo tries again to convince Stiles to let him help find Lydia. The find a shower room full of cowering patients. In the floor, there is a grate that they believe leads to miles of tunnels under Eichen.

~~~

Scott grabs Meredith's hand and begs for her help. Just as he gives up she grabs his hand and places it on the back of her neck. He is reluctant to use his claws to access her thoughts but she is insistent and he inserts them.

~~~

Kira is still firing off bolts of electricity in the morgue until she collapses, apparently unconscious. Malia is about to check her pulse when Josh shows up and says he can still feel the electricity coming off her. He says he can help Kira if Malia will help a badly burned Corey.

~~~

"This is a stupid plan," Brett tells Selene.

"Obviously," Selene says and then sighs. "But it's the only plan we have. Brett, my best friend is in there and she is dying. I already lost Allison I am so not losing Lydia too"

"Okay," Brett says and sighs. He places his hands on her shoulders. "What you're gonna do may sound impossible but if there is someone that can do this, it's you. You can do it" he adds and Selene nods. Brett nods back and lets go off her shoulders. Selene turns to the gate and lets her eyes glow their Kitsune orange.

~~~

Inside Meredith's mind, Scott follows her down corridors until they find Lydia. In the real world, Liam is waiting as Scott stands stock still, his claws embedded in Meredith's neck. Two orderlies come down the hall checking the cells. Liam slams the door to Meredith's cell and rips off the electronic card reader. He takes out the two orderlies easily but is then confronted by a very large, muscular guard who seems to growl as he rushes toward Liam.

~~~

Lydia is screaming in Meredith's mind. Meredith warns Scott that Lydia doesn't have much time before her power will consume her due to Valack's trepanation. She says Valack thinks it's worth it if Lydia can reveal the identity of the beast. Meredith says Lydia won't be able to do that until the screams in her head are loud enough to kill her. Meredith says Scott needs to find the Hellhound to get through the Mountain Ash. She says the Hellhound and the Banshee are connected and if Scott can find Parrish, he will find the Banshee.

~~~

Mason is blowing up Hayden's phone. Deucalion continues to try to manipulate her to leave him alone. He says he thinks they're going to be friends with a lot of common ground beneath their feet. She decides to go but first injects him with Tracy's venom to keep him paralyzed for a couple of hours while she finds Mason.

~~~

Scott removes his claws from Meredith's neck. He hears her whisper once more in his mind, "Save her." The door opens and the large, muscular guard stands there for a moment before collapsing forward into the room. Liam is behind him and once he makes sure the guard is down, he too collapses.

~~~

Theo has lost Lydia's scent due to the myriad of chemical and faecal matter smells in the tunnels. Stiles goes off on his own but Theo says Stiles will need to trust him. Stiles points out that he's being asked to trust a guy who killed his sister when he was 9 years old. Theo claims that he was naïve and, when the Dread Doctors showed up and claimed his sister wanted him to have her heart, he believed them. Theo claims he had no idea what was going on when his sister fell in the water and froze to death "in minutes." Stiles says he thinks Theo pushed her and that he liked killing her. Lydia screams somewhere in the tunnels. They can't tell where the sound originates because it's coming from all around them.

~~~

In an unused laboratory in the Eichen tunnels, Lydia awakes strapped down to a chair. She can hear a multitude of screams in her head. Dr. Valack turns on a device that issues an electronic hum. It seems to quiet the screaming and Valack says she should focus on the sound and his voice alone. Nurse Cross (Mandy Levin) is in a cell nearby, wide-eyed but unmoving. Valack says she wasn't as strong as Lydia. The power cord to Valack's machine, old, frayed and covered in cobwebs, begins to spark.

~~~

Scott and Liam find Parrish lying in one of Eichen House's stairwells. He doesn't know how he got there. They explain that the hospital is in lockdown and they are switching to "Plan B" to get Lydia out. They say they need the Hellhound to do it.

~~~

Corey isn't healing. Malia speculates that it's too much for him or perhaps his pain is blocking him. She offers to take Corey's pain to help him heal if Josh will absorb Kira's extra electricity. They don't trust each other so decide to do it at the same time. She grabs Corey's burnt arm and the veins in her hands begin to blacken as she absorbs the boy's pain. Josh grabs Kira and his body is surrounded by purple lightning as he roars.

~~~

In the tunnels, Stiles and Theo are both at a loss. Theo claims he wants to save Lydia but Stiles says he has other motives. He says he knows Theo wants Lydia to draw out Parrish and help him take the beast's power. Stiles knows about the claws and the search for Deucalion. Theo admits they already have the blind Alpha. He says he plans to help Parrish defeat the beast, then take its power and break its neck. He says he might not be the good guy but could be the guy that saves all their asses

Stiles suggests that Theo break one of the pipes along the wall because sound carries better through the enclosed space and they can hear better and find Lydia. He breaks the pipe and they hear Dr. Valack's voice.

~~~

Doctor Valack says he needs Lydia's help against the Dread Doctors. He says they ruined him, drove him to obsession and consigned him to professional ridicule. People thought he was a monster but he claims he was just trying to warn them to the danger of the Dreads. Lydia says he now wants her to be his eyes. He says she'll see things no one else can and, while she might not survive, she could save the lives of her friends. He produces his Dread Doctor's mask.

~~~

Scott and Liam use a lighter and an aerosol can to fire up Parrish.

~~~

Valack explains that Lydia needs to calm her brain from a "Gamma wave to a Theta" because if he tries the mask on her now it would kill her. He explains that the Dread Doctors have produced an engineered version of the Beast. He says it's not fully grown and still bound to the teenager chimaera inside. It still requires the Dread Doctor's protection. Lydia says Damnatio Memoriae. Valack says the Beast was a man first, a human killer in the late 1700s. He says the Dreads are trying to get it to remember itself. Valack claims that when that happens the teenager inside will be gone.

~~~

Josh helps Corey off the morgue table. He seems to be healed but parts of his skin are still blackened. Malia explains that they're still locked in but there is a Plan B involving Mason and Liz. Kira says they've got the blueprint of the building and will find the transformer shed behind the building.

~~~

Masonis in the middle of leaving Liam a panicked voicemail as he stands outside behind Eichen House. In his hand is a photograph of the transformer shed Kira mentioned.

"Liam, call me back. Dude, I have no idea what to do, and I'm panicking. I'm completely and totally panicking. I drove around this building, like, four times, and I can't find this transformer shed. Well, actually, that's partially right, because I found where the transformer shed is supposed to be... but, it's not a shed anymore. It's a wall. Like, a very big wall. So, I mean, I tried calling Hayden, and she still isn't here, and I heard alarms go off, and now I don't know what to do. So, Liam, just call me."

Mason sighs and hangs up the phone before turning around and looking at the so-called transformer shed, which, like Mason said, is now a huge, thick concrete wall that is at least twelve feet tall.

"I can try to burn a hole in it?" Liz proposes.

"Do we have a better idea?" Mason asks.

"Not really" Liz replies and Mason sighs.

"Go for it" Mason then agrees and Liz's eyes glow yellow as she makes a fireball appear in her hand.

~~~

Theo and Stiles zero in on Lydia.

~~~

Valack explains to Lydia that the teenager inside the Beast might be someone she knows. He says it was a success where Theo and the others were failures. Lydia says they looked through the list of genetic chimera's and found everyone. Valack says they missed one. Perhaps they overlooked a way that someone could have two sets of DNA. He says if Lydia can see the face of the teenager inside the Beast, then her friends could have a fighting chance. He says his Dread Doctors' mask can help her see.

~~~

Stiles and Theo arrive outside the laboratory. They begin banging ineffectually on the door.

~~~

The machine Doctor Valack was using to calm the screams in Lydia's head begins to spark and shuts off. The screaming returns full blast and Lydia begins to lose control. Valack picks up the mask but, as he is about to place it on Lydia's head, she screams. The mask falls away and half of Doctor Valack's head is bloody pulp.

Theo breaks the door handle and Stiles rushes in. Lydia protests that it is too dangerous but Stiles tells her to shut up and let him save her. Theo finds the Dread Doctor's mask.

~~~

"You did it!" Mason exclaims and hugs Liz.

"I actually did it!" Liz agrees excitedly.

"Mason! Liz!" Someone suddenly yells and the two turn around to be met with Hayden.

"What are you doing here?" Liz asks. "Not to sound... not happy that we got some extra help" Liz quickly explains.

"I got your message" Hayden explains.

~~~

Hellhound Parrish walks down the hall to the Closed Unit. Scott and Liam follow wondering aloud how he will get through the mountain ash. As he reaches the door, the barrier doesn't appear and Scott and Liam realise Selene and Brett aren't there. Scott and Liam pass through with ease.

~~~

In the UNDERGROUND SEWERS, Stiles is trying his best to keep Lydia standing as he leads them through the tunnels, but it's obvious that she's getting weaker by the moment, and Stiles isn't strong enough to keep her up by himself.

"Okay, you gotta try to stay on your feet," Stiles tells her. Lydia groans in pain as they continue to walk, and Stiles keeps talking to distract her from the voices. "The plan didn't work too well, so I'm gonna need your help, okay?"

"You had a plan?" Lydia asks weakly.

"Yeah. It was good on paper. Not so much in reality" The voices in Lydia's head overwhelm her to the point that she whimpers loudly, but when she and Stiles turn a corner and burst through a door, Lydia can no longer handle everything she's hearing and falls to her knees, pressing her hands against her temples.

"I... can't do it!" She yells. Stiles, horrified, turns back to Lydia to try to help her up.

"Lydia..." The walls around her start to shake, and Lydia can't help but scream at Stiles.

"Stiles, run!"

Just then, Selene appears behind Stiles, grabbing him by the shoulder and forcefully throwing him back into the adjacent hallway, where Brett catches him before he can hit the wall. Lydia lets go of her head and opens her mouth to scream, just as Selen wraps her arms around her as she screams as loud as she can. Somehow Selene dampens the sound of her voice, protecting the others from dying from the sound of her banshee wail, but the force of both the scream and whatever Selene is doing combined creates a concussive blast that rattles the walls and causes many of the bricks to be crushed into dust, which falls onto the boys in the hallway.

Scott, Liam and Parrish arived during the blast. They, Stiles and Brett cough loudly from all the dust they inhaled before turning toward the adjacent hallway, where Selene is carrying a barely-conscious Lydia toward them. All of them look shocked by the fact that they survived.

"How?" Stiles asks.

"Later. I know what to do but we gotta get her to Deaton because I don't have everything" Selene explains and they nod. Everyone starts running.

~~~

Mason, Liz and Hayden stand infront of the control.

"There's supposed to be two red levers" Mason points out.

"I fucking know, Mason. But there are ten, I'm sure you can see that" Liz states.

"What do we do?" Hayden asks. Liz sighs.

"Pull them all" Liz replies and they do so.

~~~

Liam heads for a locked gate. Scott expresses doubt about Mason's end of the plan. Liam is confident.

~~~

The lockdown is released, the metal shutters roll up off the windows and doors.

~~~

Liam reaches the gate and it sparks a little but gives way to his push.

~~~

The door to the morgue opens and Malia and Kira rush to get Stiles' Jeep.

~~~

Outside the FRONT ENTRANCE of Eichen House, Malia and Kira drive the Jeep to the front steps just as Liam, Brett, Scott, Stiles, Parrish, Selene and Lydia have crawled out of the UNDERGROUND SEWERS. Selene looks at Lydia with concern.

"Can you stand?" She asks her best friend. Selene gently sets her on her feet, though she continues to help her stay standing as Kira and Malia get out of the Jeep and look at her with concern.

"Is she okay?" Malia asks. Scott looks panicked by the sight of her and the knowledge of what she's capable of doing in this state.

"Not exactly. We gotta get her to the clinic. Fast" Selene says.

Just then, she groans in pain and falls forward against the hood of the Jeep, revealing her back has several fresh, deep claw gashes along the length of her back. The others look up to find that once again, Lydia is being held in a choke-hold by one of their enemies-- this time, it's Tracy, who is partially transformed into her Kanima form and who is sneering at the McCall Pack smugly.

"Sorry, she's coming with me" Brett growls and steps forward but Tracey pushes her claws deeper into Lydia's throat. Scott looks horrified and immediately tries to reason with her.

"Okay, Tracy, just wait. You don't know what's about to happen-" Scott tries. Tracy cuts him off and starts to slowly walk backwards with her clawed hand still wrapped around Lydia's throat.