Alright, I'll lay it out for you.
There is a young farmboy dreaming of adventure, living with his uncle on the outskirts of the Empire. An aged, mysterious storyteller informs him that once, the land was protected by heroes, guardians who used magic to defend it. This young hero learns that his father was once one of these warriors, as was the mysterious storyteller; and he can become one as well.
But- oh, no! Our young hero returns to his farm to find it in ruins and his uncle killed, by no less than the forces of the evil Empire. He swears vengeance against this Empire and its dastardly Emperor, leaving his homeland to travel with the old storyteller. This storyteller gives his life for our young farm boy, protecting him from an attack. Along the way, he rescues a princess from the Empire and joins the Rebels, leading them against a last-minute attack on their hidden base.
In Volume Two, our hero discovers that his father was actually the Emperor's right-hand man, his most trusted servant: his apprentice, if you will. He also learns that he has a long-lost twin.
He discovers that the late storyteller's plan was to further his training with the last surviving magic user, a former teacher. This aged and crippled man lives the life of a hermit in the forest, but is still able to teach our young hero much. However, at the last minute our hero decides to complete his training later and save his friends, vowing to return.
I could go on, but there wouldn't be much point. Eragon is Star Wars. I read the first two books and really enjoyed them. It was only after I read the third one and was incredibly disappointed that I began to actually analyze the story and realized how familiar it really was.