Percy Jackson is a troubled boy who finds out that he is the son of the Greek God Poseidon. He then moves to Camp Half-Blood. In the midst of this, he is blamed for stealing another god's weapons, and he sets off on a journey around the world to find it while encountering friends and enemies along the way.
The Lightning Thief is an excellent beginning to the Percy Jackson series. This book definitely shows its research on Greek mythology (it might get a touch out of hand when describing things though), as it gives all of its elements a more modern look to it. The characters are all easy to get attached too (whether you love some or hate some) and the story is quite compelling.
Overall, it's definitely worth a try. This is a must for Greek mythology fans.