This first book of the multi-author series tells of how teens Dak (a history buff and odd duck), Sera (a science nerd), and Riq (a member of the secret Hystorians society) end up as the only ones who can save the world by fixing breaks in time that changed what was meant to be. Their first mission—saving Columbus from a mutiny that was meant to fail—is a disquieting choice that I would not choose as an introduction of history to children. For starters, they are choosing to save the man who brought genocide to the Americas. And to boot, in the broken world where the mutiny succeeded, his three ships still completed their voyage with no noticable change to subsequent centuries (apart from Columbus resting at the bottom of the Atlantic).