Eldest by Chistopher Paolini

Eragon, the first Rider in over a century, is sent to Du Weldenvarden, the elves' forest, for trainingwith his dragon Saphira. They are taught by a crippled Rider pair. Eragon has trouble with his back all throughout training, a scar from his battle with the Shade. On the day of the elves' celebratin of their pact with the dragons, a mythical being heals his back completely. Soon after, he recieves news that the empire's formidable army is marching towards the Varden's encampments. Eragon has sworn to help the Varden whenever he is needed, so he flies immediately to Surda. The war that has been going on for more than a century has burst into the open, Eragon must face a friend gone bad, and a treasured hope becomes hated info....

Eldest is many wonderful stories twined together. It's the best book i've read since Harry Potter came out. Its prequel, Eragon, is equally good. I would wait 'till it's out in paperback though, it's really expensive now.