As you walk, you start hearing some voices??
Erm, excuse me? That was very unsettling, but you brush it off - Hogwarts is an odd place, you shouldn't over react over something a bit less usual, who knows it might be Myrtle trying to spook someone nearby.
But after only a minute you hear it again.
'.....soo hungryy....for so long....'
You're the only one that can hear this, you can almost sense the presence of someone...something... moving towards the passageway over there!
You run towards it.
'....kill...time to kill...'
Something is shining on the wall ahead. You approach it slowly, squinting through the darkness.