This second volume in the Percy Jackson & The Olympians series can be read alone but still suffers some of the flaws of a bridging book. Character development seemed thin despite Percy's growing maturity, and the characters were less dimensional. The plot, though interesting in outline and necessary for the advancement of the larger narrative, came off as picaresque and flimsy. There was more deus ex machina with magical objects and characteristics of this world that were not adequately foreshadowed or integrated, as well as several discrepancies in world rules. For example, Percy asserts again that his magical pen always returns to his pocket, but it certainly did not in the previous book. The tone of the first-person voice was troublingly and self-consciously "teenage," bringing one of the worst elements of much middle reader/young adult literature to the series.At his best, Riordan is poignant and astute. A speech on pp. 252-253 provides a great illustration of the conjunction of story and philosophy:"[Y:]ou are part god, part human. You live in both worlds. You can be harmed by both, and you can affect both. That's what makes heroes so special. You carry the hopes of humanity into the realm of the eternal. Monsters never die. They are reborn from the chaos and barbarism that is always bubbling underneath civilization.... They must be defeated again and again, kept at bay. Heroes embody that struggle. You fight the battles humanity must win, every generation, in order to stay human."I hope for continued moral complexity in subsequent installments.