Damn entertaining and the best book of the series so far in my opinion. Tavi learns of his heritage and the whole conspiracy (minus who really was behind the death of Septimus) comes unraveled with some pretty interesting consequences.
Butcher shows his politically medieval acumen as the jostling for power in Alera continues with the added threat of the Canim lurking to the north. Just what are they up to? And why are they building ships?
Butcher also creates one of the most loathsome villains in fiction since the Dursleys of Harry Potter fame in Senator Arnos, the arrogant, ambitious and scheming leader of the Senatorial Guard, which assumes command over Tavi's First Aleran legions on a politically-driven suicide mission. Butcher makes Arnos bleed arrogance to the point that you wish he were real so you could hit him in the face to shut him up and put him in his place. The only other time I've had a reaction this strong to a fictional character was my intense dislike at the injustice Harry experienced at the hands of the small-minded and rotund Dursley family. Again, you wish they were real so you could throw them in prison and make them suffer for their child abuse.
Butcher also creates some interesting transitional imagery as he progress through the series. This novel changes fundamental aspects of certain characters' profiles. As Tavi gains in strength and confidence, Gaius Sextus is forced on a mission in which he must restrain and conceal his power, experiencing their absence, and what it must have felt like for Tavi growing up, for the first time in his life. As Tavi comes into his own power, it's interesting to see how he uses it as compared to the First Lord, and how the First Lord deals with his lack of power compared to how Tavi lived his life in the first two to three books.
And let us not forget the Canim! The samurai of Alera, the warriors of honor and probably the smartest, most straight forward, but ruthless of all the creatures introduced so far. I find them fascinating, noble, and likable, in spite of the fact that they are trying to kill Tavi, Max and Crassus (who I've found tremendous respect for).
Ultimately, the plot is going in the direction I thought it would since about a quarter of the way through book 2. But it's predictability in no way robs from the majesty of the epic as it unfolds.
Looking forward to book 5.