Hugh's world has been completely shattered. His teacher Alustin betrayed him and turned Hugh's pact with Kanderon into her downfall. He also stole the cruelest weapon their world has ever produced, the Tongue-Eater, which is capable of stealing a language and rendering its speakers mute for one or more generations. Sabae always suspected that they were a means to an end for Alustin, but not even she predicted his quest for revenge against the Empire would lead to such blatant treachery. With Kanderon presumed dead, and only one injured council member left, Skyhold is broken and leaderless. Hugh is convinced that Kanderon isn't dead and he is willing to do whatever it takes to help her, while his friends concoct a desperate plan to stop Alustin before he unleashes the Tongue-Eater. It's a plan that will literally expose them to multiple new worlds in the process.
For the first time Bierce splits the plot between two storylines. One focuses on Alustin and his hope for revenge. The other follows Hugh's friends as they descend into the Labyrinth and use it to access other worlds. Alustin's journey focuses on rallying the former allies of the Lord of Bells, starting with the Gorgons that already owe him a favor. The whole history comes out in the process, including how Alustin came to be in Skyhold when his home territory fell to betrayal and how his best friend ended up as Commander of the Sacred Swords of the Empire. How he'd genuinely wanted to help Hugh, Sabae, and Talia, and that betraying them was his only regret. Meanwhile, the four friends are off seeing strange new worlds and implementing their desperate, possibly insane plan to deal with Alustin and most importantly to Hugh, saving Kanderon. If they succeed...they will have to come to terms with the idea that they are becoming Powers themselves.
After the action packed Siege of Skyhold this sixth book seems more laid back. Sure, Alustin is out there hatching his dastardly plot and planning to double cross some of his new supposed allies, but there is a lot less fighting than in previous books. The most interesting parts are about the other worlds they visit and the people/entities they meet. At least we finally see how the Labyrinths can be used beyond annual exams for mage students. This is also the first time Hugh has actually plotted to become more powerful, even though the kids have been warned before that being recognized as a Power is very dangerous. This book certainly opens up many possibilities for the series finale and I look forward to finding out how it all ends.