What does it take for Noah to realize how evil his sister is in the novel, Winter Fire?

Noah is a kind, gentle young man who believes his sister is innocent. He is told repeatedly all the things Dawn has done to people, including the kidnapping and murder of Tonya, but he refuses to believe it until Dawn orders that he be tied up and stopped from preventing the murders of Summer and Morgan. When he finally comes to his senses, Noah helps rescue the two girls, and he also tries to help Morgan hide the soul stone.