She knocked three times in quick succession, each rap crisp and proper. Harry's aunt Petunia opened the door with a polite smile, which Hermione had no trouble returning. "Hello, my name is Hermione Granger. My mother is starting a little service, for those families with children whom they don't feel comfortable leaving at home alone. There's no charge, and we're just trying to get the word out. Does your family have children?"