A boy named Eragon finds a dragon egg in the wilderness one day, and once his dragon hatches, it sets him off on a journey that will take him across the land of Alagalsia and beyond. Eragon acquires magical powers and a teacher named Brom, but he becomes wanted by the king for his powers as a Dragon Rider. Eragon and Saphira travel outside the boundaries of their land to fight on the side of the Varden, the enemies of the king. Eragon is able to kill a powerful wizard, the Shade named Durza, and save the Varden and the dwarves.

Eragon finds a rock while hunting in the wilderness in the Kingdom of Alagalsia. He brings the rock home to his uncle's farm, near the village of Carvahall, and asks everyone for their opinions about the rock, but no one knows what it is.

One day, the rock finally begins to crack open, and a dragon is born. Eragon puts his hand on the newborn dragon and a bolt of energy racks his body, making a silver, oval-shaped scar on the palm of his hand. Eragon hides the dragon from his uncle and cousin, and it grows quickly.

There are strangers in the town questioning the villagers about the egg, and Eragon flees. Saphira the dragon and Eragon flee, and when they return, they find Eragon's farmhouse in ruins and his uncle mortally wounded. After Eragon recovers from the shock, he decides to leave Carvahall with Saphira and Brom, who knows about Saphira's existence.

Brom and Eragon set out to search for and kill the Ra'zac, the beings responsible for killing Garrow. Brom teaches Eragon the magical knowledge from the secret elven language that will make Eragon and Saphira together very powerful.

Eragon finds a poisonous oil, so he and Brom decide to journey to the coastal city of Teirm to trace its destination. At Teirm, the witch, Angela, tells Eragon his fortune. She tells Eragon that he will live a long time, but he will have to leave Alagalsia. Eragon develops more of his magical powers while at Teirm.

Brom and Eragon travel to Dras-Leona. They find that the Ra'zac are hiding there, but their enemy finds Eragon first. Although Eragon and Brom are able to escape their enemies initially, the Ra'zac in Dras-Leona surprise Eragon and Brom, holding them hostage. The two are rescued by Murtagh, but Brom is mortally wounded by the Ra'zac. Brom dies, and Eragon buries his teacher and mentor.

Murtagh and Eragon travel on to the town of Gil'ead where they are ambushed by Urgals, and Eragon is captured while Murtagh and Saphira escape. In captivity, Eragon is drugged and confronted by the Shade, who also holds the elf woman. Murtagh and Saphira break Eragon out of the prison, and they bring the unconscious elf with them.

On the run from Urgals and soldiers, Eragon, Saphira, and Murtagh make their way through a small part of the massive Hadarac Desert. Eragon learns the Varden are located there. They are chased by Urgals to the entrance of the Varden and pulled into the mighty mountain of Farthen Dyr, which contains the marble city of Tronjheim.

Eragon meets with the leader of the Varden Ajihad and with King Hrothgar, the leader of the dwarves. Later, he tests his abilities with Arya the elf after she recovers from her poisoning by the Shade Durza. The Urgals invade at Farthen Dyr, and Eragon and Saphira are enlisted to fight off the monsters. The Shade Durza appears with the invading Urgals, and Eragon fights him to his death. Wounded and scarred in his fight, Eragon is visited by a vision that instructs him to go to Ellesmyra, the land of the elves, and he makes a promise to do just that.