Risto is ten years old and a drummer. He lives with his Aunt Serena – who becomes the source of Risto's problems. She writes a love letter to the bachelor who lives above them. But then Nelly, the new girl in the house, gets hold of the letter and thinks that Risto wrote it to her. Man, that's so embarrassing! But then Nelly and Risto end up becoming really good friends. Because one day Aunt Serena breaks her leg and Aunt Fanny helps run the household. At first the children think the old dragon is planning a crime, but then they discover she is plotting something even darker: Aunt Fanny is an old rock'n'roller...