The trio walked into school the next day and a wad of toilet paper hit the back of Molly's head. She turned around and glared as she looked for the culprit, but saw no one. She rolled her eyes and turned back around, muttering to herself.

A familiar voice protested, "All right, that's my face!"

She joined the boys and Stiles said, "Hey, dude, good decision, buddy. Good Alpha decision."

Scott nodded. "I hope so."

Stiles shook his head. "No, you know so. Then I can take -- What are you looking at?"

"Me?" Scott asked with a frown.

"You. You looking at her?"

"Her? Who her?" Scott questioned, trying to throw off the suspicion.

Molly followed his gaze. "Kira. You like her, don't you."

Scott immediately began to stutter. "No. I mean, yeah, yeah, she's okay. She's nothing new."

"Ask her out."

"Now?"

"Yes, now."

"Right now?"

Stiles rolled his eyes. "Right now, Scott. I don't think you get it yet. You're an Alpha. You're the apex predator. Everyone wants you. You're like the hot girl that every guy wants."

Scott's voice took on a confused tone. "The hot girl?"

"You are the hottest girl."

Scott frowned and Isaac appeared. "What?"

"I'm the hot girl."

"Yes, you are," Isaac said, earning Scott's puppy dog smile.

Molly chuckled softly at her friend's excitement.

During Economics, Coach yelled from his office, "Son of a bitch!" He walked into the classroom. "Mischief Night, Devil's Night. I don't care what you call it. You little punks are evil. You think it's funny every Halloween my house gets egged? A man's house is supposed to be his castle. Mine's a frickin' omelet. Oh, this? We're gonna do this again? I don't think so." He tossed the box to the ground and heard glass break. He opened said box to reveal a mug and picked up a note. ""Happy birthday. Love Greenberg.""

As soon as class ended, Isaac asked, "Barrow went after kids with glowing eyes? He said those exact words?"

Stiles nodded. "Yeah. And no one knows how he woke up from anesthesia. Just that when they opened him up, they found a tumor full of live flies, which in any other circumstance would be all kinds of awesome."

Molly stared at her friend. "Uh, no. Not awesome."

Lydia frowned at him. "Did you say flies?"

"Lydia?" Allison questioned.

"All day I have been hearing this sound. It's like this buzzing."

Molly's brow furrowed. "Like flies?"

Lydia glanced at her. "Exactly like flies."

Stiles ran into someone while they were looking for Scott. "Sorry... Hey, dude, where the hell have you been?"

Lydia frowned. "The police are leaving. Why are they leaving?"

Scott turned to her. "The police?"

Stiles shrugged. "They must have cleared the building and grounds, which means he's not here."

"Who?" Scott asked. "What are you guys-"

Lydia's lips pursed. "He has to be here. That sound, the buzzing I've been hearing? It's getting louder."

"How loud?" Molly questioned.

Lydia closed her eyes and took a moment to breathe.

They stood outside the front of the school and Stiles ran up to his dad and they talked for a few moments. When he returned, they meet up with Allison and she said, "The Bestiary is literally a thousand pages long. If I'm going to find anything about flies coming out of people's bodies, it could take me all night." She opened up a window.

Lydia walked closer to Allison. "And remember, the word in archaic Latin for fly is musca."

Allison nodded as she began climbing out the window. "Got it."

As soon as she left, Lydia turned to Stiles. "Where do we start?"

"Upstairs. We gotta go."

They ran up the stairs and walked into the art room. Molly glanced at Stiles. "Scott and Isaac are in the basement, right?"

He nodded. "Yeah, with Ethan and Aiden. The plan is they meet in the middle, in the boiler room."

A picture caught Lydia's attention as she said, "All of the wolves, all of the ones with glowing eyes are in the basement at the boiler room?"

Stiles' eyes widened at her words. "Oh, my God! An engineer could use a boiler room to blow up the entire school."

"We have to get them out of there," Molly told them in a panicked tone.

Stiles turned to her. "We have to get everyone out."

Lydia frowned. "How do we do that?"

Stiles and Molly shared a knowing smirk and he pulled the fire alarm. He smiled at them and his smile slowly dropped as he noticed the panicked look Lydia and Molly were giving. Coach was standing behind him. "Wow. Pulling a fire alarm on Mischief Night is one thing. Doing it when there's a mass murderer spotted nearby is insane! If I was four years younger, I'd punch you."

Stiles frowned. "What? Coach, that doesn't make sense."

"Oh, well, it does to me!"

"There," Stiles said, seeing Scott and Aiden.

"We didn't find anything," Aiden informed.

Scott shook his head. "Not even a scent."

Stiles checked the time. "It's 3:00, so school's over. If there was a bomb, wouldn't he have set it off by now?"

"Does that mean everybody's safe?" Aiden asked.

Everyone turned to Lydia and she repeated, "I don't know. I just don't know."

Stiles and Molly headed to his house and she laid on his bed. "These colored strings mean what?"

He met her eyes and said, "Oh, just different stages of the investigation. So green is solved, yellow is to be determined, blue's just pretty."

"And red?"

"Unsolved."

"I only see red."

Stiles narrowed his eyes. "Yes, I'm aware. Thank you."

Molly began playing with the red string and asked, "How long a detention did you get for the fire alarm?"

He glanced at her. "Everyday this week. It's okay, though. We were onto something."

"But we didn't find any proof of Barrow being there."

Stiles turned to the redhead and knelt in front of her. "Molly, you and Lydia have been right every time something like this has happened, okay? So don't start doubting yourself now."

"But Stiles, there was no scent. No bomb. And Lydia and I got you in trouble."

"Okay, look. Barrow was there. All right? You knew it. You knew he couldn't have gone off that easily." He undid the string from her finger. "And, look, if you wanted to, I'd go back to that school right now and search all night just to prove it." Something caught his eye. "Get up. Get up now. We're going to the school."

"Huh. Just got something from Lydia."

They headed to the school and met up with her.

"Lydia, what are we looking for?" Molly asked.

Stiles opened a classroom door and Lydia frowned. "That was supposed to be locked."

He nodded. "Yeah. I know. Notice anything else?"

Molly closed her eyes as she sniffed the air and said, "Chemicals. The wolves couldn't have caught his scent."

Stiles turned to Lydia. "He was here, performing minor surgery on himself. You were right."

Lydia frowned. "Then why don't I feel good about this?"

Molly looked around the room. "He was a shrapnel bomber. He was was probably here to kill someone."

Lydia looked at the blonde. "But who?"

Stiles let out a sigh. "That's what we gotta figure out. We could spread out and start looking for anything. Lydia, Molly, what are those?"

Molly followed his eyes to the board. "Those are atomic numbers."

"Is it a formula?"

Lydia shook her head. "Not really. 19's Potassium. The first two make Potassium Iodide."

"Potassium is K?"

Molly nodded, still staring at the board. "From Kalium, the scientific neo-Latin name."

"What's Radium?"

"R-a," Molly and Lydia replied.

"Kira," Stiles read aloud.

They immediately made their way to Kira's house and Molly noticed Scott lying on the ground. She ran to his side, shook him, and he stirred.

He looked up in a panic before seeing them and yelled, "Barrow. He took Kira!"

Stiles nodded. "We know. He was after her the whole time."

Scott called Isaac to see what he found and said after a moment, "All right, thanks."

He ended the call and said to them, "We have to think of something. He's going to kill her."

Lydia frowned. "I knew he was there. How did I know that?"

"Because of the flies. Right, Lydia?" Molly asked.

She nodded slowly and Scott asked, "What do you hear now?"

Lydia let out a sigh. "Nothing. I feel like I can do this. But I don't know what to do. It's like it's on the tip of my tongue, and I don't know how to trigger it. I just, I swear to God, it literally makes me want to scream."

"Then scream, Lydia."

She did so, and Stiles and Molly covered their ears. She took a moment to think and said, "It's not flies. It's electricity."

Stiles' eyes widened. "Wait a second. Barrow was an electrical engineer. He worked at a power substation."

"What substation?" Scott wondered.

They climbed into Stiles' Jeep and he drove to the substation. As soon as they arrived, Stiles turned to face Molly and Lydia. "Okay. Both of you, wait here, all right? Just wait for the cops to come."

Lydia frowned. "Me? Wait, why? And why does Molly need to stay here?"

"Because she can use some sort of weapon if something attacks you."

Molly nodded. "We'll be okay, Lydia."

Stiles left and moments later, Beacon Hills went dark.

Molly frowned. "This can't be good."