When Molly had found the spellbook in the thrift shop, she had been initially nonplussed to discover that the instructions seemed to be written in what she recognized as Middle English, thanks to having read Chaucer in school many years before. After much effort, she translated enough of the introduction to figure out how to use the book. She wrote her translation down on note paper and stuck in the front of the book. She worked out that all the user had to do was to concentrate on what kind of spell she wanted to cast while holding the book in her hands. Then when they opened the book, it would open to the spell they wanted. Interestingly, the spell itself had appeared to be in Latin. She kept the spellbook hidden inside her desk in her room, relying on the assumption that none of her daughters would ever go snooping in her room.
Had Molly bothered translating more of the introduction, she would have known that the spellbook could only be used by certain people. A person had to be "magic sensitive" to make the book work for them. Such people were very rare. Molly was magic sensitive, and so she had somehow subconsciously sensed the magic in the book when she had found it in the store. What she also didn't know was that someone else in her household was magic sensitive, her twelve year-old daughter, Hannah. The book would have been useless to Miles or Emma, but Hannah would be able to use it if she found it.
When Miles had been transformed into Nellie, Hannah had sensed that something was wrong, even though she couldn't say what. She looked at Nellie and saw her beloved older sister that she had known her whole life, but somehow, she saw someone else, too. At least - a hint of someone else. A boy? Why would she look at her sister and see a boy? As the days passed, she became convinced that something had happened, and that somehow her mother was behind it.
One day, when Molly, Nellie, and Emma were out of the house, Hannah snuck into her mother's room. Something drew her to her mother's desk. Searching it, she found the spellbook. Impulsively, she took it and ran from her mother's room. Taking the book to her room, she opened it up. She found her mother's partial translation and read it .
A magic book?, she thought, Does she actually believe in this stuff? But if it was real, it would explain what had happened.
Hannah resolved to try a spell and see. The spell she decided to cast was....