Professor McGonagall smiled honestly at her, shaking her head. "The reason I wish to talk to you has nothing to do with you having broken the rules. Not exactly at least." She pointed at the door on her right. "Before we go through that door and I put in a word for you three, I need an honest answer to a question from you, Miss Granger. No matter what answer you believe to be the right one for my help, it is of utter importance that you will not lie to me or yourself."