Sherlock was on a case that had bodies dropping every night, and the thing that made him a little nervous? He didn't understand the reasons, the killer, the motivation, and it was always each body had bite mark on their sides of their necks, exactly on the cartoid arteries... What was even more strange? They were sucked dry of blood.

He was trying to put the puzzle pieces together as he sat at his study in his apartment, more like a lab, then he heard a knock, getting up and opening the door.