It takes place on some planet (perhaps ours) that is fundamentally tectonically unstable, with earthquakes, rifts, volcanoes and other fun stuff happening all the time, sometimes enough to destroy almost everything. There are certain people with powers to control the earth's energy. Despite and because of their powers, they are feared and loathed, usually killed when discovered or often sold to The Fulcrum a special school for them where they are disciplined and trained and then used as weapons/tools to protect the land from the earth. There is a lot more going on that I won't get into here, entire histories of various peoples, other creatures and even giant crystal obelisks that hang in the sky.
The book is three narratives, following three different storylines that slowly weave together towards the end. Like Anne Leckie, this trilogy deals with contemporary issues such as slavery and colonialism (what I endearingly call "woke sci-fi") and integrates them skillfully into the setting and plot, so that you are thoroughly entertained while subtly questioning our own reality. This is what science fiction is supposed to do.
It's not perfect. The Syen character has that "angry" trait that I see with a lot of authors where they lean on simplistic anger to add conflict to situations where it doesn't feel natural. It starts to get annoying in the early and middle parts of the book, where she is always snapping and sarcastic even though anybody at that point would be more resigned and just live with the situation (of being with somebody they don't like). So much emphasis is put on this anger that when the expected evolution comes (she learns to like and even love the guy), albeit quite novel and interesting, it's not very satisfying or convincing.
All that being said, I still walked to the bookstore and bought the second book so I can find out what will happen next.