Where my story took off from

I consider my idea to be well thought out, but the process to make my story into the rough form it is now came from a much more vague source. I was supposed to create a short story for my 12th grade English class while incorporating twenty vocabulary words as a homework assignment. The evening before the assignment was due, I had decided to rest for a short time until my mother had returned from work. While asleep I dreamed of myself running down a sparsely lighted corridor with torches spaced out along the walls. The first question that came to mind while in my dream was "Why am I running?" As I ran, I noticed the stone walls at my sides were old and probably from some structure that was once used often, but had been abandoned after some time.
I continued to run without any knowledge or regard to how long. Soon my pace seemed to quicken and my breathing grew heavy. My body moved frantically to and from what had looked to be openings out of the corridor. Each time I approached a door, the way disappeared from my sight and I was facing yet another section of the wall.
After trying my hand at another passageway, I slowly turned to where I had fled from. Though curious, I did not expect to see what came soon after. A six-foot-five, heavyset man slowed to a thundering halt and then began to walk toward me, causing the ground beneath me to shake. Disregarding the fact that I was scared out of my mind from the sudden sight of him as he emerged from the shadows, I took off running again only after noticing a specific detail about the giant. He had with him an axe! My eyes immediately gathered that the axe he held was not only sharp, but had a two foot spike toward the handle's base. The axe head itself was curved and the blade, which was offset away from the handle, a span of three feet. I could not stand the thought of me being killed in such a brutal manner, so I continued to run down the corridor while hoping to outlast my pursuer.