Percy Jackson always thought he was just another ADHD, dyslexic kid trying to survive middle school without setting off any fire alarms (again). But when his pre-algebra teacher turns into a Fury and tries to kill him, he learns the horrifying truth: the Greek gods are real, they're still causing drama, and he's one of their kids. After being sent to Camp Half-Blood, a summer training ground for demigods, Percy discovers he's the son of Poseidon, one of the Big Three - which is about as rare (and dangerous) as it gets. To make matters worse, someone's stolen Zeus's master lightning bolt, and Percy is the prime suspect. While Percy struggles to figure out who framed him, he's joined by two companions: Grover, his satyr best friend, and Annabeth, a battle-smart daughter of Athena. But this time, there's a fourth member on their quest - a strange girl named Thea Rowan.

Basicaly S.H.I.E.L.D gets Percy as a recruit.