Answer: She discovers the power of love to fight the darkness of hate
Step-by-step explanation:
In the book, A Wrinkle in Time, siblings Meg Murray and Charles Wallace along with their friend Calvin O'Keefe embark on a journey to a planet under the control of a dark force known as IT.
When they get there Charles is captured but the rest manage to escape and now Meg has to go back to save her brother. In the process of saving him she discovers that she must use the power of love for her brother to fight and conquer the darkness of hate that the IT possesses. When she does so she is able to free her brother and they escape together.