Filch: Anyone here, my sweet? Come on. Hermione: Filch is gone. Ron: Probably thinks this door's locked. Hermione: It was locked. Harry: And for good reason. They were looking straight into the eyes of a monstrous dog, a dog which filled the whole space between ceiling and floor. It had three heads. Three pairs of rolling, mad eyes; three noses, twitching and quivering in their direction; three drooling mouths, saliva hanging in slippery ropes from yellowish fangs. It was standing quite still, all six eyes staring at them, and Harry knew that the only reason they weren’t already dead was that their sudden appearance had taken it by surprise, but it was quickly getting over that, there was no mistaking what those thunderous growls meant.