Rating: 1/5 (did not like it)
tl;dr: Deeply tedious haunt story with perhaps two scares in a book needlessly long for the genre
The Good: Well, this is honestly difficult. I thoroughly disliked this book. I've only read one other by Cross and it was pretty good, so I'm assuming this was just poor selection on my part considering the scope of her oeuvre and size of her fanbase.
I enjoyed the setting. Hardstone as a Victorian jail brought to a shameful degree of readiness in time for use by myopic neoliberal bureaucrats rang true to recent experience. It had a lot of potential.
The Bad: Woof. To begin with, the most obvious problem for a book of this nature is that it isn't scary. It isn't. I can think of two times that really built tension, but they were fleeting and ultimately pointless. The one that got me the most, which I shan't spoil but that seems at the time as if it is pivotal to the story, is wholly incidental. It just doesn't matter after it happens. It's baffling. Cross spends considerable time establishing a frightening if/then scenario and then defangs it when it comes to fruition. Why bother? Who knows?
Beyond the conceptual failure of the genre, the book is bloated with unnecessary detail about the backstory of characters with dubious role to play. The most frustrating thing about this inclusion is that it interrupts the storyline to go back in time to provide backstory on a character you may not have met yet, or if so only in passing. It makes it very hard to care about the intricacies of their lives. I'd say the book is probably between 50-60% longer than necessary in large part due to this provision of needless detail. Now, part of that detail is tied to the eventual explanation, but because the explanation is so mind-numbing, there is no vindication for having waded through all of the superfluous detail. Instead, there is resentment.
The Ugly: The concept that underwrites the entire novel-- the big reveal, the driving force, the explanatory factor, the haunting of Hardstone jail-- is baffling, riddled with holes. The book is predicated on some absolutely astounding power on the part of one character and some equally astounding naivety on the part of another. I was so angered by the stupidity of the reveal that I set the book down, stormed into the kitchen, and ranted madly about it to my wife.
Worse, though, somehow, than the imbecilic irregularity of the conceit is the utter lack of meaningful results for the worst villain in the book. This character is wretched, despicable, and then utterly cured as part of the aforementioned conceit. I found no satisfaction whatsoever in the story or its conclusion.