1. Unveiling the Demigod Identity: Percy begins to realize he has unusual abilities and encounters strange creatures when he's attending a boarding school. His best friend Grover reveals himself as a satyr, a protector of demigods.
2. Camp Half-Blood: Chiron, the activities director at Percy's school, takes him to Camp Half-Blood, a safe haven for demigods. Percy meets other young demigods and begins training to control his powers.
3. The Prophecy of the Oracle: At the camp, an oracle delivers a prophecy that predicts Percy will bring either great glory or disaster. Along with his friends Grover and Annabeth, daughter of Athena, Percy sets out on a quest to find Zeus' stolen lightning bolt, which Poseidon is accused of stealing.
4. Retrieving the Lightning Bolt: Their journey leads Percy, Grover, and Annabeth to the Underworld, where they encounter a variety of mythological creatures. They battle monsters and solve puzzles to retrieve the stolen lightning bolt.
5. Betrayal and Confrontation: Percy uncovers a plot involving Ares, the god of war, who seeks to use the lightning bolt for his own nefarious purposes. Percy and his friends face Ares in battle.
6. The Return to Olympus: With the lightning bolt safely returned to Zeus, the gods decide whether Percy should face punishment for his actions or be hailed as a hero.
7. The Camp Half-Blood Family: Regardless of the outcome, Percy finds a home and family among the demigods at Camp Half-Blood, realizing he belongs in the world of the gods and monsters.
Throughout the story, Percy also navigates his personal struggles and comes to terms with his newfound identity as a demigod. "Percy Jackson and the Lightning Thief" sets the stage for the subsequent books in the series and introduces readers to the world of Greek mythology and demigod adventures.