Percy works the nightshift

The underground - which was usually abandoned - was alive tonight. Alive with fear. I wasn't sure how, on my search for the missing child, I had gotten myself into the old system. After all, the entrance had been bolted shut for years. But alas, here I was, in the cold, damp underground, water dripping onto my cap.

This was a very strange case indeed. I work night shifts as a security guard at an amusement park, so it was surprising when, at around eleven o'clock, a young girl came up to me, somehow in the park (she must have been staying at one of the resorts). Crying hysterically, she explained that her friend Britney had been taken. She lead me to where Britney was last, and I followed two pairs of footprints out of the park and to the entrance of the old train station. The chains around the door had been slashed open. I thought at first they had been cut, but when I turned my torch on to get a better look, I gasped. The doors were covered in long, deep gashes, looking to have been made by some kind of animal clawing frantically, and the sign warning to 'KEEP OUT' had a large bite taken out of it.
But the strangest part was, the footprints I had seen alongside the little girl's looked human, and the bitemarks on the sign had been made with blunt teeth...

"You've really gotten yourself into trouble now, Percy" I whispered to myself. I knew I really should have called some sort of higher authority, but I was here now.
I'd dug my own grave.
I started down the tracks, hearing nothing but my feet squelching in the wet rot between the bars, and my own breath echoing in the empty walls.
My light went off with a click. Everything was pitch. I slapped the back of the torch wildly until it came back on and I was once again breathing heavily in the old underground. The batteries were a little faulty, and hitting the torch a few times usually works, but I wasn't usually looking for a kidnapped child in the middle of a train system with a possible murderer when it happened. Wait, was I in this part if the underground before?

I was lost, and that's when I heard it.

It was a long, loud, grating sound. It rang loud in my ears and echoed all around me. There was no way of telling where the noise was coming from, it seemed. The only way I could describe it was like nails on a blackboard, and I wasn't far off. It was claws on the walls...
"I have a gun!" I lied. I was trying to scare off whoever was there. In reality, the only dangerous item I had was a broken Swiss army knife and my clumsiness. The reply that came was the giggle I had heard in so many of my nightmares. Only this time, it was much deeper. Much louder. Much more horrifying...