Fort becomes entangled with legendary creatures and foes in this thrilling fourth novel in the fantastical series from the author of the New York Times bestselling Story Thieves! The future has been saved, but at a cost: Fort Fitzgerald has been expelled from the Oppenheimer School, and some of Fort's friends have been lost in time. But time is the one thing Fort, Rachel, and Jia don't have, as they'll soon be facing one of the eternal Old Ones, the Timeless One, for the fate of the world. If they lose, the Old Ones will return, and humanity is doomed. If they win, the Old Ones will still return, and humanity is doomed. Because the Timeless One can see every possibility, and plan for it. How can Fort and his friends defeat a creature like that? And what does this all have to do with the real-life Merlin, from King Arthur's days?