Percy, expelled from six schools for being unable to control his temper, learns the truth from his mother that his father is the Greek god Poseidon, and is sent to Camp Half Blood where he is befriended by a satyr and the demigod daughter of Athena who join him in a journey to the Underworld to retrieve Zeus's lightning bolt and prevent a catastrophic war.

"Twenty-year-old Violet Sorrengail was supposed to enter the Scribe Quadrant, living a quiet life among books and history. Now, the commanding general--also known as her tough-as-talons mother--has ordered Violet to join the hundreds of candidates striving to become the elite of Navarre: dragon riders. But when you're smaller than everyone else and your body is brittle, death is only a heartbeat away ... because dragons don't bond to 'fragile' humans....