Sequel to: The last magician.

Esta thought the Book of Mysteries held the key to freeing the Mageus from the Order's grasp, but everything she knew about magic was a lie. Now the Book's power lives inside Harte, and he needs to be able to control it. To bind the power, Esta and Harte must track down four elemental stones scattered across the continent, but the Order isn't alone in its mission to crush them. In St. Louis, the World's Fair hides the first stone, but an old enemy is out for revenge and a new enemy is emerging. And back in New York, Viola and Jianyu must defeat a traitor in a city on the verge of chaos. -- adapted from jacket

"Esta and Harte set off on a cross-country chase through time to steal back the elemental stones they need to save the future of magic"--,Provided by publisher.