Disclaimer up front - this is my sister's web comic. So when I say I really enjoy this entry, you can keep that context in mind. But I really do like this book, and I feel like this series is improving with each volume.
First, let me say this - this is a cold open, so if you want to start here, don't, and if you don't remember where we were, go back and reread the last couple chapters of the last book, or the previous chapters online. It might otherwise be pretty confusing. Tren and his friends have been captured, and while the person who did it might be more friendly than the last person who took them prisoner, he still seems highly untrustworthy.
While the rest of the cast has varying reactions (Jaith's reaction to all the botheri in the city is adorable), Tren himself is learning a lot more about himself - why he can't cast magic (or at least thought he couldn't), where the spell comes from and what his new captors want of him.
But just because the villain of the piece is in jail doesn't mean he's out of the picture. Power will always sing its siren song, and old prejudice runs deep.
Overall, this continues to be a really entertaining fantasy tale, with some unusual and engaging worldbuilding and I do rec it if that sounds like your cup of tea.