DURING THE THIRD ATTACK, Hazel almost ate a boulder. She was peering into the fog, wondering how it could be so difficult to fly across one stupid mountain range, when the ship’s alarm bells sounded. “Hard to port!” Nico yelled from the foremast of the flying ship. Back at the helm, Leo yanked the wheel. The Argo II veered left, its aerial oars slashing through the clouds like rows of knives. Hazel made the mistake of looking over the rail. A dark spherical shape hurtled toward her. She thought: Why is the moon coming at us? Then she yelped and hit the deck. The huge rock passed so close overhead it blew her hair out of her face. CRACK! The foremast collapsed—sail, spars, and Nico all crashing to the deck. The boulder, roughly the size of a pickup truck, tumbled off into the fog like it had important business elsewhere. “Nico!” Hazel scrambled over to him as Leo brought the ship level. “I’m fine,” Nico muttered, kicking folds of canvas off his legs. She helped him up, and they stumbled to the bow. Hazel peeked over more carefully this time. The clouds parted just long enough to reveal the top of the mountain below them: a spearhead of black rock jutting from mossy green slopes. Standing at the summit was a mountain god—one of