A chilling and unsettling novel set in the claustrophobic atmosphere of a country house over one day and night. A sense of real menace underlies the majority of the story making for uncomfortable reading, but it's very effectively done. There is also something surreal about the set-up, not quite magic realist but certainly bizarre.
The characters are a strange, disparate group, but believable enough within the parameters set by the novel. Certain elements of their pasts and personalities remain unclear, which adds to the surreal feeling of the novel. If anything it's a little overwritten and slow in parts, but you can't argue with the effectiveness of the prose in conjuring up the sinister ambience and an increasing sense of tension.
I felt the ending let the story down a bit, although I won't say more than that to avoid spoiling it. Certainly the central section of the book is the strongest. There are a couple of events that could be considered plot holes but they can be excused in the context of the genre. It can't be described as an enjoyable read, at least not for me, although readers who like ghost stories and similar may like it more.
I would recommend this to readers who enjoy psychological thrillers, suspense novels, surrealism/magical realism, or ghost stories. Whilst I personally didn't love it, that has more to do with my personal taste. The skill of the author in writing this demonstrates her ability and so I would happily read another novel by her.