At its core is a story of a sorceress investigating a small offshoot of believers, but the tale quickly becomes a multi-layered conspiracy tale we don't see a lot of in fantasy. Familiar-looking prisoners, warring power factions, things quickly expand out and devolve into a substantial situation.
The book itself is a fast read and a lot of fun. There's a lot going on, with a great setting and some interesting choices made along the way. The big complaint, for me, is that the old writing precept of "show, don't tell" is one that could have been applied a lot more in this book. For the type of epic this tries to be, a little less on-the-nose descriptions, especially of character motivations, would have taken this fully out of the "self-published" place and into something that might get more attention.
This, however, is still a great read in spite of that caveat. A very enjoyable read that reads a lot smoother than you'd expect for the genre.