Disturbingly sad, religious dystopian horror 
The main character remains unnamed throughout the story with an ending so abrupt and painful it has you questioning whether the author had more to write or if this could've been added as a short story in the last novel, 19 Claws and a Black Bird
after the MC escapes a cruel wasteland of environmental chaos, she joins the Sacred Sisterhood and deemed an Unworthy and writes her story in broken diary form with scrap paper and ink made from horrific sources 
The sacred sisterhood has a weird religious hierarchy, the unworthy have opportunities to be chosen for the Enlightened but all positions seem a version of torment, punishment and sacrifice
When a stranger appears and is chosen as an unworthy the mc starts to change and reveal more about herself, her past and the bounds she creates
please research the content warning! even though this is adult horror, this is one of those times where readers would appreciate content warning pages