The sound was like a clap of thunder in the small space.

The iron latch clicked into place with a sickeningly solid sound.

Then came the scrape of the heavy brass key turning in the lock.

The lock was an old double-bolt mechanism.

I heard his footsteps ascending the remaining stairs beyond the door.

Then, there was only silence.

The vault was plunged into absolute, thick darkness.

I stood at the bottom of the steps, my breath coming in ragged gasps.

The air felt instantly colder, heavy with the smell of old dust.

I reached into my pocket and pulled out my phone.

The screen lit up, casting a weak blue glow on the damp walls.

The signal indicator still showed zero bars.

I ran up the stone steps, my heart pounding in my ears.

I reached the iron door and threw my weight against it.

It did not budge.

I pounded on the cold iron with my fists.

“Harrison!” I screamed.

“Let me out!”

Only the echo of my own voice answered me.

I leaned my forehead against the cold metal, trying to breathe.