Just tell me, Percy, do you still have the birthday gift I gave you last summer?" I nodded and pulled out my camp necklace. It had a bead for every summer I'd been at Camp Half-Blood, but since last year I'd also kept a sand dollar on the cord. My father had given it to me for my fifteenth birthday. He'd told me I would know when to "spend it," but so far I hadn't figured out what he meant. All I knew that it didn't fit the vending machines in the school cafeteria.