The house is unwelcoming and dark as I push the door open, and a blast of cold air hits me in the face. I turn to Thomas and Carmel.

"If you want to change your minds-"

"No," says Carmel flatly. "We're coming with you."

"Thomas?" I ask. "Are you still in?"

"Yeah," he grins. "Team Ghostbusters, right?" I give up.

"If you say so," I sigh as I step over the threshold into the house. "Both of you, stay behind me."

"Why? Are you saying we can't fight ghosts?" Carmel objects.

"I already explained," I say patiently. "I'm the one with the knife."

"And you're the only one who can use it?" Her voice is skeptical.

"Actually, yes." The one time I let someone else try almost ended in disaster for both of us. "It's... I don't know. I'm the only one who can actually kill a ghost. You could do some damage, perhaps, but..." I trail off, shrugging. It's not that I haven't tried to find out why the athame only works for me, but information is limited. It's not the kind of thing that Google has the answers for. There's nothing more to say, so I continue into the darkened room.

"What are we even looking for?" That was Thomas.

"I'm not really sure." I wouldn't admit to it under torture, but I'm terrified. Cas asked for our help. What kind if monster can hurt someone already dead? "Hello?" I call out. "Is anyone there?"

Silence. Nothing. Empty rooms in an empty house. There's no one here. And then-

"Help me!" The cry is barely audible, but it bounces around and off the walls. It's not Cas. Whoever it is, I don't recognise them.

"Who's there?" I ask. Silence. "Who's there?"

"You have to help us!" It's a different voice this time.

"Where are we?" Another wails.

"I don't know where I am!"

"Help! Help!"

"Shut up, you idiots!" My heart leaps. It's Cas. I've found him. "He'll hear us!"

"Who's 'he'?" Thomas whispers. "Do you think it's the same one Cas wrote about on the mirror?"

Before I can answer, another voice shouts. "Shut up yourself! It's your fault I'm here! I'd have dealt with him years ago if you hadn't lost the athame when you died!" It's a girl's voice with an English accent. I don't know her, but from the way she's screaming at Cas, I'd say she knows him. Or, if she didn't before, she does now they're both trapped in this house.

"How was I meant to know? I though I was the only one! Why don't you fuck off back to Scotland?"

"I'd love to, but incase you haven't noticed, I can't!" This has gone on long enough.

"Cas!" I call up the stairs. "Where are you? It's me!"

"Anna?" His voice floats down the stairs.

"Yes! And Thomas and Carmel."

"Go Team Ghostbusters!" Thomas cheers. I am going to strangle him when this is over. I really am. Carmel laughs.

"Yeah, except in this case, we're busting the ghosts out."

"We're in the attic!" Cas shouts. "There's some kind of spell on the door, but I don't know if it works on living people. You might be able to get in."

"Wait, how many of you are there?" I ask.

"Loads. Too many. You've got to get them out of here."

"There'd be a lot less if I'd been able to do my job properly!" The girl Cas was arguing with snaps.

"Yeah, well, you couldn't, so-"

"Alright, enough!" I yell. "We're coming to find you. Just hold on, okay?" Dead, living- who cares? They're just as bad as each other.

We're half way up the stairs when Cas' voice sounds again.

"Anna, Thomas, Carmel, go back. Go back down stairs and go outside. Just go outside and wait."

"What?" I frown. "Why?"

"Please. Just get outside as fast as you can. Don't come back for at least an hour. Seriously, just go."

"But-"

"Oh no. You're not sending them away." It's ghost girl again. "Anna, right?" She addresses me for the first time.

"Yes?" What does she want? What's going on?

"You're the ghost hunter, aren't you?"

"Yes..."

"So don't go anywhere. You're the only one with half a shot at killing him."

"At killing who?"

"Me, I think is what she means." A soft voice speaks from behind me. Thomas and Carmel gasp. I don't dare turn around. Instead, I focus on the steps in front of me when I speak.

"Move up the stairs so I'm between you and him. Don't say anything. And you-" I address whoever else is on the stairs with us "-you don't hurt them. I'm the one you want to talk to."

"Yes, I do want to talk to you. But your little friends won't be going anywhere. Turn around, Annie."

"Just do as he says, please," Cas begs.

"Your boyfriend knows what he's talking about. Turn around." Slowly, I move to face the voice, clutching the athame tight. Then I see him. And I see Carmel and Thomas.

I can't help it. I open my mouth and scream.