This is book 3 in the Eragon series, which was supposed to be a trilogy but now claims there is one more book coming. Best to start at the beginning, and this book doesn't resolve very much. It doesn't end in the middle of a battle, but it's still very much in the middle of the war.
This book is of a piece with the earlier ones as best I remember them. It's pretty cliche. It has a lot of battles. I don't know much about real battles, but these descriptions seem a lot more hokey than many. It feels driven by the author's whim, with a couple of points of major deus ex machina, and some interactions and events that don't seem to make sense. Despite all that, it has that indefinable something that makes me want to keep reading. I think this is a weaker book than the previous two, and its weaknesses annoyed me a bit, but I didn't want to stop.
7 out of 10.
**** PLOT SUMMARY -- MASSIVE SPOILERS ****
We start out the book with Eragon and Roran scouting the Ra'zac's base, breaking in, killing them, and rescuing Roran's love Katrina. The Ra'zac are apparently irredeemable by nature, but they are sapient beings, and these are the last of their race, so it kind of ticks me off that Eragon is unwilling to offer them any quarter, not even to promise to remember them as valiant after they are gone. Eragon contrives excuses to send Roran and Katrina back to the Varden with Saphira while he stays; he doesn't want Roran to know that he thinks Sloan (Katrina's father, who betrayed them to the Ra'zac) is there. Saphira really doesn't want to be separated, but Eragon insists. He finds Sloan, who's been tortured and blinded, but he decides that he will make himself some kind of a monster if he kills him. So instead, he curses Sloan to never be able to see his daughter again and sends him to the elves, where in theory, if he truly changes himself, his true name will change, the curse will be lifted, and the elves will cure his blindness. Eragon makes it safely back to Saphira. 12 of the most powerful elf spellcasters show up to be his guards, including Blodgharm, who has midnight blue fur. Eragon of course spends most of the rest of the novel avoiding his guards and apologizing to them for not letting them be there when they were needed. He has a fight with Murtagh and Thorn, which he wins this time with the extra support, and then gets sent off alone to try to arrange that a favorable new dwarf king is selected and to be there for the coronation. He nearly gets assassinated by the dwarf clan that hates him, but this is enough of an outrage that his guy gets put on the throne. Saphira arrives for the coronation and magically restores the Star Sapphire that she broke to save Eragon in the battle with the Shade in the first book. Right about here, Eragon learns a big secret about dragons, unhinted before now. A dragon can put its soul into a gem and give the gem to another person. This allows communication over any distance and allows the dragon to live even if its body is slain. Then the two of them go to Ellesmera to meet with their mentors. Eragon gets the metal to make the sword he needs, and the great elf swordsmith who swore an oath to never make another sword possesses Eragon's body and makes the best sword he's ever made. Eragon names it Brisingr (the word for fire in the ancient language) and discovers that whenever he says the name it gets all flamy. Oromis and Glaedir suddenly decide that instead of continuing to hide, they should join the fight now. Glaedir gives Eragon his heart of hearts. Eragon also learns that Brom was his father. Eragon arrives in Feinster just in time to save Arya and demonstrate Brisingr's power. They enter the keep just as the bad guys are trying to create another Shade. Eragon is distracted in this battle because just at that moment, Galbatorix has discovered Oromis and Glaedir and kills them. Arya delivers the killing blow to the new Shade, so they are both Shadeslayers now.
While Eragon was off by himself, Nasuada was trying to decide if Roran was fit to be a captain. She had him serve under an incompetent jerk. Roran killed almost 200 enemies by himself and singlehandedly turned a total defeat into a total victory, but because in doing so, he disobeyed stupid direct orders and instead applied good tactics, he is flogged, in the name of discipline, and he and the army that he saved with his heroics tolerate this. Eragon marries him to Katrina. Roran is an even more unbelievable figure than Eragon, because Roran is only human, with no magic, and he does it all with only True Love to empower him.