The Verdant Cage by Jess Lourey

Rose Allgood lives behind the towering stone Wall that has protected her people. No one leaves. No one fights. And no one questions why.

When Rose's mother is murdered and her twin brother framed, she knows it's up to her to clear his name. Determined to find the truth, Rose follows a trail of hidden messages, forbidden knowledge, and whispers of a past no one dares to remember.

The deeper she digs, the surer Rose becomes that her mother's death was no accident. And the Wall isn’t just keeping something out. It may be keeping something in.