12 days since Mrs. Greystone and Ms. Morales were reported missing 4 children who are determined to bring back their mothers and 2 worlds . . . Until their mother vanished, the Greystone kids -- Chess, Emma, and Finn -- knew nothing about the other world. Everything is different there. It's a mirror image, except things are wrong. Evil. Their mother tried to fix it, but she and an ally got trapped there, along with Ms. Morales, their friend Natalie's mom. Now the four kids -- brave Chess, smart Emma, kind Finn, and savvy Natalie -- are determined to rescue everyone. To do so, they have to go back: into the other world, where even telling the truth can be illegal. Chess doubts he can ever be brave enough. Despite all her brains, Emma can't seem to break the code. With everything spiraling out of control, Finn has to pretend he's okay. And for Natalie, the lies of the other world include some she wishes were actually true. What if she's gotten so used to lying she no longer knows what to believe?