The book opens with a brief prologue concerning past events, beginning with the creation of the world by seven gods. One of the seven, Aldur, fashions an orb from stone and creates within it a living soul. This orb becomes known as the Orb of Aldur. One of the other gods, Torak, forcibly takes the Orb from Aldur and tries to make the magical stone submit to his will. The Orb retaliates, burning and maiming Torak throughout the left side of his body, and burning out his left eye. The Orb of Aldur is later recovered by Belgarath the Sorcerer, King Cherek, and his children. Cherek's youngest son Riva, the only one without ill intent in soul, is able to hold the Orb without being consumed by its fire; thus all of his descendants are responsible for guarding the Orb, during which time Torak will not prevail and have dominion over the world.
The story then begins in earnest with descriptions of the experiences of a boy named Garion, who is being raised on a large, prosperous farm. It tells of his earliest memories in the kitchen of his Aunt Pol; and describes how he meets Durnik the blacksmith, Garion's early games and friends, and something of the romance between himself and local girl Zubrette. It also introduces his contact with "the Story-teller" who, unknown to Garion, happens to be Belgarath himself; Garion's vision of a man robed in black who casts no shadow, later known as Asharak; Chamdar; and a "dry voice" that speaks in his mind which appear to be separate from his own consciousness. The reader later discovers that this is the Voice of Prophecy, or "Necessity" which occasionally talks to Garion, and even takes action through him.
When the storyteller, also known as "Mister Wolf" (a name given early on by Garion), arrives with news of the theft of a mysterious object by a thief whom no-one will name, Mister Wolf and Aunt Pol leave Faldor's farm to chase him down, reluctantly allowing Durnik to accompany them. Garion, Aunt Pol, Durnik, and Mister Wolf are joined later by Silk/Kheldar, a Drasnian prince, spy, and thief, and by Barak, a Cherek warrior and Earl of Trellheim famous for his immense size, love of ale, and unmatched prowess in battle. Garion finds himself in the company of these diverse and mysterious companions, visiting several cities as Mister Wolf follows an invisible trail of the thing that was taken. Eventually he and his companions are arrested and taken to a meeting of monarchs.
After being introduced to the kings, Aunt Pol and Belgarath spend most of their time in council with the kings, leaving Garion more or less on his own. Garion begins to have doubts about his actual relation to Aunt Pol, whom he ultimately discovers is the 3000-year-old sorceress Polgara, and that Mister Wolf is her father, the 7000-year-old sorcerer Belgarath. This causes some tension between Garion and Pol until it is resolved at the end of the book.
While roaming in the palace at Val Alorn, Garion sees a green-cloaked man act suspiciously, but does not tell anyone of this. A few days pass and Barak decides to go wild boar hunting in the near by forests. Against Aunt Pol's advice, Garion also goes. While in the forest Garion chances on a meeting between the green cloaked man mentioned earlier and another man about trying to spy on the current meeting between the kings of Aloria. Before Garion can tell anyone he is attacked by a wild boar, luckily killing it but becoming injured and unconscious in the process.
Garion proves himself uniquely useful through all of this and shows his great potential by revealing to the Monarchs the presence of the green-cloaked spy, who is shown to be connected to a traitorous noble. Moments later, this noble and his men attack the castle from within, but are defeated. Garion himself is almost captured, but escapes. Later, he and the other protagonists leave again in search of the Orb, taking an Algarian prince named Hettar with them. As they leave, Garion learns that Polgara is the sister of his most distant female ancestor (identified in the prologue as Queen Beldaran, wife of Riva), justifying her claim to be his aunt. Having learned this, Garion embraces Belgarath as his grandfather and addresses him as such throughout later books.