The Lost Hero (Heroes of Olympus, Book 1) by Rick Riordan, Hardback with no dust jacket, First Edition, published by Hyperion Books, Disney. 2010.
ason is pretty confused when he wakes upon a school bus on a trip to the Grand Canyon with no idea who he is or how he got there. Earnest Piper acts like Jason's girlfriend, and goofy Leo thinks he's Jason's best friend, but Jason can't remember either of them. Before he can ask many questions, all three are attacked by storm spirits and rescued by a Camp Half-Blood chariot. The newly revealed heroes have barely broken in their cabin bunks when they're called on a quest to rescue Hera (who knows who Jason really is) from dark forces stirring in the Earth -- giants and much more. Riding off in a metal dragon expertly fixed by Leo (Hephaestus' son, of course), the three seek out the nearly-as-dangerous wind gods to help find Hera. But Piper has another secret quest: Her father has been kidnapped by another giant who wants to trade her friends' lives for her father's freedom -- a horrible choice to make.