A stranger in the house

That night she shouted my name in a loud and usual voice down the hallway. "Hmm! it's 10:20pm" I mumbled "why is she shouting my name like that", walking very fast towards her. "What happened here?" she demanded in an angry voice.

The blue rug carpet was covered with a pool of bloody foot prints. "i have no idea how those got here" I said, "I have been on my desk studying". The look on her face changed from anger to confusion and then fear. This ofcourse we both realised meant someone else was in the house. Hmm! ...

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As we followed the trail we realised the foot prints we realised it started from the back door that was left unlocked.
And the prints showed not trace of it leaving the house. A stranger was in the house.