The inheritance cycle is a 4 book series written by Christopher Paolini, with one movie adaptation that was terribly done. The movie plot followed roughly the story of a farm boy becoming a dragon rider of old but that's about it. Main Characters in the story were changed and in some cases even removed. The author himself even spoken out that he disagrees with the direction they took with his story. For all the true fans out there who are clamoring for more Eragon both on screen and off we have good news.
The official paolini.net has a couple of Q&As I dug up specifically talking about the inheritance cycle, while he is currently writing his first Sci-Fi Epic he has plans for us to return to the land of Alagaësia once again. Book 5 is coming, we can continue to follow Eragon, Saphira, and Arya on their journey to restore the peace keeping dragon riders of the past.
Paolini specifically mentions that we will see old faces and lots of new as he continues to weave his web of tales, all the unanswered questions of Angela the mysterious herbalist, Murtagh and Thorn, and even Nasuada. Who for anyone for read this series have a deep attachment to all the characters involved. Now on the silver screen front Paolini himself is putting for a "faithful" adaptation as he put it. We can all only hope our prayers are answered.