The Lightning Thief
by Rick Riordan
Crusty owns a water bed store in West Hollywood, about a block away from the gates to the Underworld. He likes to lure his customers into lying down on his water beds, which are exactly six feet long. If the customer is shorter than six feet, he stretches them with ropes. If the customers are longer than six feet, he chops off whatever part hangs over the edge. Annabeth and Grover get tied up in two of Crusty's bed, but Percy is able to save them by outsmarting Crusty. He asks Crusty to try a bed for him, and then he lops off Crusty's head. Crusty is the last big obstacle that Percy and his friends must face before entering the Underworld.