[You just came back from somewhere.While on the way, you feel someone is following you.But many times looking back, no one was there.The streets are very quiet,Only you were there at that time,ALONE.]

A few moments later [You've reached your house. You closed the door and rushed to rest. You slowly fall asleep...Before someone knocks on your door,The sound came from the living room]

Knock knock

Who's that?