Curiosity got the better of you. After all, you would have certainly heard yelling through the thick door if that loud bang had been something unfortunate.
You decided it is better to open it quickly -- so you’d have no second thoughts. The door handle is cold and damp from condensation. Here goes... You squeeze your eyes shut and yank the door open in one motion.
You weren't prepared for what you saw. Nothing. Well, very little. As your eyes adjusted, you could make out the silhoette of a figure by a window. It was night time, and there were no street lamps. The man was hunched over, shaking violently. In his left hand, he held a notepad.