At age eleven, Taylor Markham was abandoned by her mother. At fourteen, she ran away from boarding school, only to be tracked down and brought back by a mysterious stranger. Now seventeen, Taylor's the reluctant leader of her school's underground community, whose annual territory war with the Townies and visiting Cadets has just begun. This year, though, the Cadets are led by Jonah Griggs, and Taylor can't avoid his intense gaze for long. To make matters worse, Hannah, the one adult Taylor trusts, has disappeared. But if Taylor can piece together the clues Hannah left behind, the truth she uncovers might not just settle her past, but also change her future.