A/N In this episode, before Giles comes up with his theory, Willow suggests Marcie might be a witch. I think this makes a lot of sense as an explanation given how Marcie somehow pulls Cordelia up through the ceiling of the closet she's changing into her dress in. Marcie is shorter than Cordelia, yet she somehow reaches down into the room Cordelia's in and lifts her up through the ceiling tile? A straight lift of about eight feet holding a struggling 120 lb (approximately) girl, all with no apparent effort? Yeah. 😜
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"Marcie Ross." Diana read the name. "Mr. Giles, are there yearbooks stored in the Library?"
"Yes, I'll get the most recent one." He returned a couple minutes later and handed it to the teens, who began paging through it.
"There she is." Xander pointed at the picture. "I don't recognize her."
"Neither do I." Cordelia shook her. "The info under her name says she played the flute in band."
"Maybe she was the one playing the music I heard." Xander suggested. "But none of this explains why she'd be living in the school or why she's gone missing in the first place, if she's not a ghost."
"Unless she's become invisible somehow." Mr. Giles suggested.
"We need to leave, now." Xander grabbed Cordelia's arm in one hand and Faith's with the other. "I'm getting one of those feelings and I think Mr. Giles' right and I also think she's listening to every word we say. And I'm kicking myself for not realizing it sooner."
The others followed quietly behind him with Mr. Giles bringing up the rear.
"She could be following us and we wouldn't even know it." Jesse stated, once they were outside.
"No." Faith shook her head. "The closest she would have been was in the ceiling, otherwise I would have heard her breathing when we all stopped talking when Xander told us to."
"I think I would have too." Xander agreed. "I'm not sure, but I think that being the Hyena King left me a few extras. Doesn't mean she isn't trying to catch up with us though."
"Hyena King?" Cordelia asked.
"I got possessed by a hyena during the trip to the zoo last month."
"And now I'm feeling like you've told me that before!" Cordelia threw her hands up. "Why would you tell me you'd been possessed at one point? Why would I need to know that?"
"Later." Xander answered. "We need to call Mason, he and his team have equipment that can track our invisible girl down."
"What kind of equipment could a hunter team possibly have that would locate an invisible girl?" Mr. Giles asked, clearly confused.
"HVG, also known as heat vision goggles or thermal imaging goggles, they can read heat signatures through almost any material."
"Xander," Jesse looked confused. "you just met Mason yesterday and I was there, he didn't mention anything about what kind of equipment he had or what he'd be training you to use to hunt vampires. How can you know that?"
"Vampires are room temperature and humans don't have the kind of senses a Vampire Slayer has, which means they need to compensate and the military has all kinds of equipment that can be repurposed to hunt vampires."
"Have you been studying alternatives means of hunting vampires?" Mr. Giles asked curiously as Diana called Mason and filled him in on their suspicions.
"No and I have no idea where that bit of trivia just came from. But I think it makes sense."
"You ruined everything!" A voice screeched from the direction of the school and the group swung around. They couldn't see anything. "Why are you protecting her? It's all her fault!"
"Cordelia's?" Xander asked, stepping in front of both Cordelia and Faith. "Because she doesn't know who you are? I don't know who you are, have we ever met?"
"We've gone to school together for years, Xander Harris. You never saw me either, but you, I don't care about. Cordelia treated me like crap for years and yet she never saw me! Well now she can't see me because I'm invisible and I can treat her like crap. She deserves it!"
"Why are you invisible, Marcie?" Mr. Giles asked. "How did this happen?"
"It's Cordelia's fault!"
"How could it be my fault?!" Cordelia demanded.
"Because I tried to make you go invisible and it backfired somehow. It's your fault!"
"You used Magic." Xander stated, as Faith eased down behind him and grabbed some dirt in her hand.
"Yes, I used a book I found in the Library. I could make things move and I wanted to understand why and it seemed the perfect way to punish Cordelia, by making it so no one could see her. But it didn't work! It made me invisible and I can't fix it! I don't understand why!" As Faith popped up and threw the handful of dirt straight at the voice as Xander leaped forward at the same time and grabbed the girl when the dirt hit her face and eyes and wrapped an arm around her neck and squeezed. A moment later and she went limp.
"Xander," a voice said. "where the Hell did you learn how to do a sleeper hold correctly? Let alone on an invisible person?" Mason and his squad, fully geared up, including HVGs, stood there staring at the young man and then one of them stepped forward and got a pair of cuffs on the girl.
"I have no idea."