"What makes you 'you'? Chess has always been the protector of his younger siblings, Emma loves math, and Finn acts silly so he will be adored. They've been a happy family, the three of them and their mom. But everything changes when reports of three kidnapped children--who share the same first and middle names and exact birth dates--reach the Greystone family. This bizarre coincidence makes them wonder: Who exactly are these strangers? Before Chess, Emma, and Finn can ask their mom, she takes off on a mysterious work trip. Puzzling clues left behind lead to complex codes, hidden rooms, and a dangerous secret that will turn their world upside down."--Page 4 of cover