A Promise

My assignment for Round 1 was Suspense/Thriller, the action required was walking upstairs, and the story must include the word promise. 

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I had found him. I crept up the stairs. The knife in my shaking hand. I climbed silently. The monster stirred. My heart raced. I peered up the dark stairwell that threatened to swallow me. Shivering. I raised the knife. He sprang at me growling,

I screamed feeling my feet slip. Falling downward. I grabbed for the railing, He was there, he lunged at me, hitting my arm. His heavy body continued past me, his momentum carrying him over the railing.  I drove the knife into his heart as he fell.

“A promise kept.” I shrieked. “You killed my family.”