This is book three in the Codex Alera series. To know who the characters are and why they're in the positions they're in, you need to start from the beginning of the series.
If I wanted to dislike this book, there are a lot of things I could complain about. Important plot points are so predictable that I could see them coming, and when I'm engrossed in a book, I seldom realize that stuff was obvious until after it's happened. The heroes are so excessively heroic that they border on trite. The battles where first one side and then the other is described as too powerful to possibly stand up to leave the reader wondering which descriptions we weren't supposed to believe. Despite all that, the book grabbed me by the throat and just wouldn't let go of me. The battle scenes -- which the book is stuffed with -- are tense and exciting despite the inevitability. The violence manages to skate along the edge of being too gory for me to enjoy it without ever quite falling into the pit. Major developments in the overall story arc make it seem clear where we're ultimately heading, though it will still be exciting to get there. Since there is a big ongoing story arc, and this isn't the last book in the series, there are of course things hanging fire, but we have reached a reasonable place for a pause. Still, I'm frustrated that I'll have to wait at least until I get to a bookstore for the next one.
9 out of 10.
**** PLOT SUMMARY -- SPOILERS ****
Tavi starts out the book being assigned to assist Maestro Magnus on an archaeological expedition to the Roman ruins (a much stronger hint than we've had before of where this world comes from). Then Max shows up, and after an assassination attempt in which Tavi has his first confirmed kill, Max delivers new orders. They're being sent to join a new Legion that Gaius is forming. Tavi, under an assumed name, is being assigned as Third Subtribune Logistica (a junior assistant quartermaster, but an officer); Max will be a centurion. Tavi gets a crash course in Legion fighting techniques as they arrive, and then promptly pisses off the Tribune Logistica (catching him in some routine graft) and spends the next several weeks inspecting the latrines. Things are very tense for Max, because his stepmother has been assigned as the Tribune Medica (chief doctor) for the legion. Eventually we pick up some background: Lady Antillus has been trying to eliminate Max as a rival to her blood son since Max was a small child. She hasn't succeeded because Max' furycraft is too strong and she's not willing to do anything she could be caught at. But it sets the stage for Max and Crassus, the brother, to bond later on.
While this is going on, Isana has been at a big meeting of the Dianic League with her forced patron, Lady Aquitaine, and has managed to meet Bernard and Amara. Just when they should be having a nice family dinner in one of the swankest restaurants I've ever read a description of, the stars turn blood red and an army of berserk assassins overrun the restaurant. Many important Citizens are killed, but Bernard, Isana, and Amara escape, aided by Fade who's again revealed that he's not really a simpleton. And two important people are taken as hostages. Kalarus declares open rebellion, and with the hostages holding two important lords back, things look ugly for the Crown. Aquitaine, the traitor in the first book, is forced to ally with Gaius to keep Kalare from winning. Amara, Bernard, and Lady Aquitaine are dispatched to rescue the hostages. Meanwhile, Fade, revealed as Araris, is starting to die of an almost untreatable poison he picked up in the attack, and Isana starts a long and desperate effort to save him.
With the start of the civil war, Tavi's legion is suddenly on active duty, although guarding a strategic bridge isn't likely to be an important battle. But it becomes much more interesting when a lightning bolt wipes out all the other officers of the legion, and Tavi is suddenly in titular command, with only a couple of centurions who actually know anything. And then Kitai shows up and leads him to see that an enormous force of Canim have landed practically on his ass and burned their ships, and also to witness Lady Antillus treating directly with the Canim.
From this point forward, it's several hundred pages of furious battles. Between some brilliant tactics and using his personal knowledge of the Canim to plan effective strategies, Tavi manages to direct the battle to a successful conclusion and to wipe out Sarl, the actual villain among the Canim. Tavi thought he was manipulating Nasaug, the military leader of the Canim, but in the end, he thinks that Nasaug maneuvered him into getting rid of Sarl. The Canim military and the magic users don't like each other at all. But Sarl was a monster, and Nasaug is an honorable enemy; there's actually long-term hope of reconciliation. Meanwhile, the hostage rescue is successful. Finally, Isana manages to reach Araris, who's decided to die, in a trance, and manages to shame him into being willing to live again. When they both wake up, Isana realizes that he's been in love with her for years.
What Isana wasn't telling anyone before, but we've finally learned in flashbacks in this story, is that Tavi is her son, not her dead sister's, and that Septimus, the Princeps, was the father. Araris, the greatest swordsman of the age and personal bodyguard and friend of Septimus, wasn't protecting him at the end because he was protecting his pregnant lover. And he's hidden himself as the simpleton slave Fade to be close to Isana and Octavius. I felt like an idiot for not having seen the hint in Tavi's name before, even though I've suspected for at least one book that he was actually Septimus' son. And finally, the reason that Tavi has no furies is that Isana deliberately suppressed them, because she wanted to protect him from becoming Gaius' heir and therefore a target for shit like that which killed Septimus.
In the epilogue, we learn that First Spear Marcus, one of the key people who held the legion together, is the traitor Fidelias in disguise, apparently now working for Gaius again and serving as a double agent. With a real Imperial heir, he sees hope. And Tavi and Kitai seem to be able to control the furylamp in their bedroom -- so it would appear that Tavi's physical growth isn't the only thing that finally flowered once he got away from Isana's protective clutches.