Opium is an undercurrent of the Nikara empire. The war with the Federation of Mugen brought it to these shores and only the powers of the Trifecta, the Vipress; The Dragon Emperor and the Gatekeeper who went to the gods and begged for power, have kept the Mugen Federation at bay.
The Dragon Emperor is dead, decades later, the Gatekeeper is missing and the Vipress sits on the throne and the Mugen Federation is still a threat.
In this world war orphan Fang Runin finds herself having to make a choice. She can marry or she can fight for her right to be in the Military Academy in Sinegard. There she finds a lot of obstacles and powers she didn't realise existed. Powers that are officially forbidden.
There's a lot in here and a lot of things that you can see will have implications later in the series. It led to another bad decision book club moment where I kept "just reading to the end of a chapter" until I finished the book. There were a few moments where the bad decisions felt more plot driven than character driven but I'm sure this will be worked out in later books. It's going to be an interesting ride. There were interesting philosophical moments where the author was looking at belief and how magic and belief could be linked and how it could have implications when you didn't believe.
I hope there's a more human side of the Mugen Federation in later books because so far they're very single-minded and not very nice.