Eragon is hunting in the Spine, a mountain range, and is chasing a deer when he finds a shiny blue sapphire, which is later found to be an egg.
Eragon travels back to Carvahall, where over the course of the next several days he tries to find ways to sell or get rid of the egg. He goes to the local storyteller to find out what the egg could be.
Eragon put the egg in his room when suddenly in the night the egg starts to make noises, like musical notes. After a while the egg cracks and eventually hatches. Eragon fins that the stone was a dragon egg.
Eragon leaves Carvahall with Brom the storyteller, and starts travelling with Saphira. During their journey, they come upon a town that was ransacked by a race called the urgals. After they leave the town they continue onwards to find the Ra'zac who killed Eragon's uncle.
Eragon and Brom are on the hunt for the Ra'zac in Dras' Leona, where the Ra'zac live. They enter the city where Eragon encounters the Ra'zac and uses magic, taught by Brom, to escape.
Eragon and Brom encounter the Ra'zac and during the encounter Brom is injured and Murtagh, son of Morzan, arrives to drive off the Ra'zac. Later on Brom dies from his injuries and Saphira turns a cave into a jeweled grave for him.
Eragon and Murtagh go to Gil'ead to rescue Arya the elf. She reveals that she is the person who put Saphira's egg in the Spine. They continue onwards to meet the Varden, a rebel group against the empire, to seek refuge in a dwarven city.
Eragon and Murtagh arrive at Farthen Dur, the city where the Varden have their HQ, and are welcomed by some and hated by others. They are brought into the city and are brought to the Dwarven king, Hrothgar, to decide their fate.
The Urgals attack Farthen Dur, the Dwarven city under the mountain, and Eragon and Murtagh fight with Saphira and the dwarves to fend them off. Afterwards Eragon regroups with everyone else in Tronjheim and the book ends.