This is "Book Two of the Enduring Flame", the direct sequel to The Phoenix Unchained, picking up where that left off. It would be a mistake to read this book without first reading Unchained. Unfortunately, it's a bigger mistake to read this one without continuing to the as-yet-unpublished third volume, because it ends in an unbearable cliffhanger.
This book is very much the continuation of the previous volume. It's a fairly interesting world, though definitely cliche, and it continues to be very frustrating how the main characters are supposed to be 17 but are treated and often act as though they're more like 13. I wonder if somewhere in the earlier books in the series, they happened to mention that years are shorter in this world, and I have forgotten it. The most Interesting theme is how people can rationalize doing terrible things and talk themselves into believing that they're good and right.
The story is engaging, but the ending (or should I say, the running out of pages) is extremely frustrating. I'm willing to wait until the next book to see how it all turns out, but to be cut off here without knowing what just happened leaves this reader feeling abused. 6 out of 10.
**** PLOT SUMMARY -- MASSIVE SPOILERS ****
At the end of the last volume, Harrier has just been given the Three Books and told he is to be a Knight-Mage. He and Tiercel have gone off on their quest to find the Lake of Fire. Kareta, the unicorn who delivered the Three Books, seems to be a very spoiled 6 year old in personality. Harrier eventually manages to smack a little bit of empathy into her head and she starts behaving better. She reveals that her staying with them is a Mageprice. They leave the Elven Lands and find a man almost at death's door. Harrier has been resisting doing any Wild Magic because he's afraid of Mageprice, but confronted by the dying man he goes ahead and does the healing. The immediate power cost knocks him out for a few days. His Mageprice is to become an apprentice. It turns out that the man is an exiled Telchi sword master. Because Harrier is an untrained Knight-Mage he is able to soak up the teaching of the master. They make their way to Tarnatha'Iteru, one of a series of oases on the edge of the great Isvai desert, and Tiercel spends months trying to find any information about the Lake of Fire.
While this has been going on, we've also followed the thoughts of the villain. Bisochim believes that all he's trying to do is to find a way to save Saravasse, but he's twisted his beliefs into the idea that the Balance the Wildmages serve is a False Balance, and the True Balance requires allowing the Dark back into the world just a little bit. He foresees a war to convince the rest of the world that his way is right, and he wants to save his Isvaieni from it, so he converts them to this True Balance heresy and takes them to his secret paradise beside the Lake of Fire. But the huge band of warriors can't handle being cooped up together in paradise, so to keep them from killing each other, he sends them off to find the small tribe that disappeared. He just plans for them to spend a lot of time looking before they give up, but they come upon the body of one of the Isvaieni Wildmages that Bisochim killed because they wouldn't convert, and somehow come up with the idea that the cities on the edge of the desert are an enemy they must eliminate, because the rest of the world would have to come through them to get to the heart of the desert. They wipe out all but two of the string of cities before they arrive at Tarnatha'Iteru.
When the army shows up, Tiercel puts a shield around the whole city, but he can only keep it up as long as he stays awake. They think that the besieging army is desperate and will be weak for lack of water after a few days, but when Tiercel's shield fails, they prove to be less weakened than expected. They slaughter everyone in the city, but take Tiercel and Harrier prisoners. As soon as Tiercel wakes up, he calls Ancaldar (whom he'd sent off to hide to not frighten the locals), who rescues them. They try to follow the trail of the bad guys, but discover that they are being held off by magic. They wind up taking shelter in Abi'Abadshar, a mysterious city which was apparently a place where elves and dragons lived before the Great War -- not the war in the first trilogy, the one before that. This is the same place that the missing Isvai tribe were hiding. Tiercel has figured out that the place must have powerful shields that are still working after all this time because Bisochim has not been able to find them. So he, Harrier, and Ancaldar explore farther and farther down until they get to the bottom level. And Ancaldar disappears, poof, and Tiercel collapses, saying his Bond is gone. Even though they know that the bond ending would mean his death. But there is no trace of Ancaldar and Tiercel can't feel him, or draw on his magic.
Harrier and the now powerless Tiercel decide that it's their duty to try to follow the road that was blocked to them before, since they somehow think that without Ancaldar the magic won't hold them off any more. Shaiara the leader of the Nalzindar (the lost tribe) insists on going with them, acknowledging that she probably won't come back.
In the epilogue, Bisochim has just received word that the captives were rescued by a dragon. He concludes that his enemies have a Bonded Mage who can pull the water he's drained out of the desert back into it, and he's determined to try to finish his plan to summon the Endarkened, have it make him immortal so Saravasse doesn't die when he does, and then bind it so it can't destroy the world.