Emma and Martín are settling into their new home in Chicago and getting ready to start at their new school. When they learn they'll be in separate classes for the first time, they aren't sure they can face so much change alone. But when life gets stressful, the siblings now have the perfect escape--into the book of legends!

They enter the creation story of when the giant Ometecuhtli made the world. As soon as they arrive, they realize they have a major problem: it takes a magical object to activate Emma's necklace and open the portal home, but how can they find one when nothing exists yet?