I have read this book many times and it still remains as my favourite book. It follows a 12 year old boy named Percy Jackson that is suddenly attacked by monsters at his boarding school. He finds out that his best friend is a satyr (half-man, half-goat), and he also finds out that he is a half-blood (a child of a Greek god). He gets taken to a camp (Camp Half-Blood) for other kids that are children of Greek gods, where they get taught how to read Ancient Greek and how to fight like a warrior. After spending a few days at the camp, and without finding out who his father was, he is finally claimed by the God of the Sea: Poseidon. This spelled great trouble Percy, as this meant he was a child of the Big Three.
After World War II, The Big Three (Zeus, Poseidon and Hades) swore an oath that they would not have any more children as they were too powerful and dangerous. Zeus had already broken this oath when he had a daughter named Thalia. Thalia was killed by monsters three years previously, and as she was dying Zeus took pity on her and turned her into a pine tree. This pine tree now protects the borders of Camp Half-Blood so that no monsters can get into the camp (unless they are summoned by someone within).
Anyway, the world is at risk because Zeus' master bolt has been stolen, and he is framing Poseidon saying that Percy had stolen it. So Percy gets sent on a quest (along with Annabeth and Grover), to retrieve the master from the Underworld because they believe that Hades has taken it. Along the way, Percy encounters various monsters (e.g. Medusa, Echidna) and gods (e.g Ares, Dionysus) overcomes them all. When he confronts Hades, it turns out that he doesn't have the bolt and that Percy had it in the backpack that Ares had given him. Someone had also taken Hades' helmet of darkness.
In the end, it turns out that Percy's friend Luke was the one that stole both of the items and tried to cause World War III so he could resurrect the Titan Lord Kronos, who planned to over-rule the gods and start a new era. Anyway, Percy manages to return the 2 items back to their owners and prevents the war. Then Luke tries to kill Percy and escapes.
I really enjoy reading the Percy Jackson series, because it is written in first person (which catches my attention) and it is all about Ancient Greece in modern times. I give it a 10/10.