In this, the second of five books of the Belgariad, Garion learns he is not a simple farm boy. He is a powerful, but untrained and unknowing sorcerer. Garion is a necessary yet not quite willing participant along with his grandfather, the sorcerer Belgarath and Belgarath's daughter the sorceress Polgara (Aunt Pol) in the search for the Orb of Torak.
If they are successful in their quest the balance of power among the kingdoms will remain as is and they will prevent a cataclysmic war in the land.
The first book in the series is Pawn of Prophecy.