Santiago, an Andalusian shepherd, sleeps in a ruined church and has a recurring dream about treasure at the Egyptian Pyramids. He visits an old woman to interpret it and then encounters Melchizedek, King of Salem, who tells him about the Personal Legend.

Santiago arrives in Tangier and is immediately robbed by a new 'friend.' Stranded with no money, no language, and no way home, he faces his first real test: despair or adaptation. He chooses adaptation and finds work with a crystal merchant.

Santiago joins a caravan crossing the Sahara and meets the Englishman, a scholar seeking the Alchemist. Their contrasting approaches — books vs. observation — define the novel's epistemology. The caravan stops at Al-Fayoum oasis.

Santiago falls in love with Fatima at the oasis well. He reads a powerful omen in the sky — two hawks in battle — and warns the tribal chieftains of an impending attack. His prediction saves the oasis and draws the attention of the Alchemist.

The Alchemist guides Santiago across the final desert toward the Pyramids, teaching him that all things are one — the Soul of the World — and that the Personal Legend is not a destination but a relationship with the universe. They are captured by tribal warriors.

Facing execution, Santiago communing with the desert, the wind, and the sun, and appeals to the Soul of the World itself. A sandstorm erupts. He becomes the wind. The soldiers release them in awe.

The Alchemist parts from Santiago at a Coptic monastery. Santiago reaches the Pyramids alone, begins to dig, is beaten and robbed by refugees — and one of the robbers accidentally reveals the location of the real treasure: back in Spain.

Santiago returns to Spain, digs beneath the sycamore tree in the ruined church, and finds the chest of gold coins and gems. He sends a share to the gypsy woman, plans to return to Fatima, and hears her voice on the wind. The journey ends where it began.