Feeling oddly compelled by his words and the strange cast of the stones, Hermione reached for the tie of her robe and began to undo it, but she wasn't going fast enough and he had grown impatient. He moved her hands away and undid the tight knot easily, pulling the robe off her shoulders sharply so that she gasped. It pooled around her ankles in one heavy heap and she was left nude, her skin pebbling in the cold air.