"Clariel" is the fourth novel in Garth Nix's Old Kingdom series, and was released in 2014, a decade after the previous book, and almost two decades after the release of the first book, Sabriel. The book is a prequel, set 600 years before the events of the main book. The book is the story of Clariel, who was introduced as a villain in the later books, as a powerful undead monster, and describes how she became a villain.
Clariel is a typical teen girl who has moved to a new city and is going to a new school, and is unhappy with the changes. Well, she isn't really that typical: she is living in a high fantasy medieval world where magic, and the presence of magic creatures and the undead, are normal. Even within that context, she isn't normal: her mother is a wealthy goldsmith, active in the guild system, which is currently supplanting the kingdom's traditional monarchy, which she is also related to, the cousin being her king. Clariel feels confined and angry when her parents enroll her in a finishing school full of snotty rich kids, and she starts getting angrier and angrier at her surroundings. Not just angry: it turns out she is a berserker, meaning that her lack of temper has a supernatural edge to it. This book moves pretty quickly, so after a few establishing character moments, Clariel is put into a rapidly developing plot involving free magic creatures (demons) and a plot by the guilds to wrest control of the kingdom from the royal family. Will she be able to get out of these troubles, without giving into her berserker nature? Since the story has a foregone conclusion (we already know that Clariel becomes "Chlorr of the Mask" in the next few centuries), it might seem like we know where this is heading, but of course, there are a few twists along the way.
I didn't mention in my opening paragraph, but this book is classified as Young Adult. This shows up in only a few ways: parts of the plot (new girl at school), as well as the action being a little quicker paced, and certain things, such as sexual topics, are glossed over. But otherwise, the Young Adult label doesn't really change that this is a very innovative and well written fantasy novel.
More important than that distinction is the distinction between fantasy and horror. This is the month of horrorquest, so while I was going to review this book anyway, I want to talk about how it fits in the genre of horror. This is a book that features the concept of the undead, that has other grotesque and evil creatures, and that is about how a woman becomes an evil necromancer. There is also the psychological counterpart of that horror: Clariel's fear of being trapped, and her anger at anyone who tries to do so, provide the internal component to the story's horror. So is this story horror, fantasy, or is trying to assign between the genres a pointless task? Despite this book having many elements that would objectively fit into the horror genre, I would classify it more as fantasy. Part of that is a certain literalness of the story: magic and the supernatural are presented in a way that is so internally consistent and almost mechanical, that the edge of the surreal or eerie that horror requires isn't present. Some of it also might be due to the Young Adult genre: the pacing of the book, and the level of disturbing content, kind of disallow the book becoming a full horror story. I don't have any single answer for this question, it seems like a subjective distinction, but while it has many of the outer trappings, I would say this story is not primarily a horror story.