The past and present unravel into staggering truths in this can't-miss installment of the New York Times and USA TODAY bestselling Keeper of the Lost Cities series told entirely from Keefe's point of view.

Please be careful. Please be happy. And PLEASE forget all about me. It'll be better for everyone that way.

Those were the last words Keefe Sencen wrote to Sophie Foster before he ran away to the Forbidden Cities. He didn't want to leave, but it was the only way to keep his friends safe while he figured out how to control his scary new powers and searched for answers about his past.

What he found was so much more than adventures in Humanland.

Where did he go? What did he do? And who did he meet while the rest of his friends worked to solve the mystery of Stellarlune? The answers go far beyond anything anyone could have ever imagined and give Keefe the power to change his destiny.