The final book in the Codex Alera does a great job of tying up all of the plot lines without tripping up and also continues the job of changing your perception of what you thought you knew already.
Tavi is aware that his grandfather has died as the Great Fury Alera has visited him and is making him (and Kitai) undergo training from hell on their journey home to Alera. This is so when they arrive Tavi is prepared to deal with the realities of war with the power available to him. He hides this from people but his increasing abilities become obvious particularly once in Alera when people find out Gaius is dead and Tavi cements his abilities with some rather extravagant shows of power (ice ships propelled by constant wind, accidental city destruction, etc.).
The war is progressing poorly though everyone acknowledge Attis (declared to be Tavi’s ‘younger’ brother) to be doing a good job. Isana and Amara even support him, as do we the readers, as we now understand he was loyal to Septimus and the kingdom and personally hated Gaius as he blamed him for Septimus’s death. Unfortunately his ex-wife Invidia who is now a servant of the Vord Queen does not share that – her desire for power that saw her responsible for Septimus’s death has not changed and she really becomes our greater scope villain – tragic because of her pettiness.
It all returns to Calderon where this story starts – a defendable valley and a committed force facing down millions of enemies. It seems hopeless but the faith in Tavi is never lost and through his new abilities he makes it just in time. And then Tavi does the Tavi thing of aiming for the most dangerous solution possible – take out the Vord Queen directly and using the Great Furies of Calderon to do so. This is actually a sad scene as the Queen is lost and confused and regards Tavi and Kitai as her parents. On the other hand Invidia gets what she deserves after more attempts to be treacherous.
There is a happy ending here but with an acknowledgement that they may have stored up pain for later (like 100-200 years later). Whilst there is space for a sequel I think I like these characters too much to want to see other people in this world – a problem I had with Raymond Feist as every character you liked died as time moved one. This is still one of my favourite series and is a 5 star for me overall.