In the dazzling conclusion to the Greystone Secrets series from New York Times bestselling author Margaret Peterson Haddix , the Greystones and their doubles, the Gustanos, must team up to save the alternate world--before both worlds are lost.
All secrets are revealed in this page-turning, suspenseful story that shows the importance of teamwork, telling your story, and taking action when it matters most.
As book three of the Greystone Secrets s.