Jonnie is the last princess of the Crystal Bearers, once a powerful people. When she was a baby, the metal army destroyed what was left of them, and now it is hunting her. Her watchmen keep her just out of the metal army's reach, but she has spent her seventeen years running and hiding. Instead of standing by while her watchmen keep risking their lives for her, she decides to learn how to fight alongside them.

On the journey to hone her skills, long hidden secrets about her people reveal a connection between the Crystal Bearers and the metal army that only fuels Jonnie's will to defeat it. But the more she learns about her own powers, the more she realizes she may be responsible for the metal army - and the destruction of her people.