There's a scuffle outside before a very aggitated Filch bursts through the door to the party and drags in a protesting Draco, who's yelling his usual threats of 'telling his father about this'.

Filch turns to Slughorn, addressing him curtly. "I discovered this boy in an upstairs corridor. He claims to have been invited to your party, sir."

A beat of silence passes, and in those few painful seconds, Draco's grey eyes meet yours.