It's been a few months since Emma and Martín moved to Chicago. When they first arrived, their family thought outgoing Emma would adjust quickly and shy Martín might have a harder time making friends. But surprisingly, Martín is fitting in just fine, while Emma wants to go back to Mexico more than anything.

She might not be able to go back to their previous home, but she can visit Mexico in the book of legends! And even better, this time the twins are joined by their abuela on the adventure. The book brings them into the story of Princess Hapunda and Lake Pátzcuaro. When an enemy tribe demands that Hapunda's father hand her over to them, she faces a difficult choice: go with their enemies or refuse and risk her people's safety.

Can the twins find a way to help the princess out of the tricky situation, or is this a tale without a happy ending?