Quick-take: A slow burn with a weak ending.
Dr. Montague is committed to proving the existence of the supernatural, and he feels he has found a very interesting specim, a haunted house called "Hill House". He sends out letters inviting a group of strangers to spend some evenings in the haunted house. 2 young ladies reply along with the future owner of the house. They all meet at the house and begin their stay.
It is hard for me to review mystery novels because each minor plot reveal is (supposedly) expertly designed to shock and intrigue to lead the reader to the next important reveal, leading up to the big finale. Therefore, I try to focus on the craftsmanship and skill of storytelling of the novel and whether or not I enjoyed it.
So just let me be clear in this regard: I did not enjoy this book. I found it simply boring. At first, I thought maybe it was just a slow burn, which is OK. There is some charm to the main character (which I will get to). However, by the time I got 3/4 into and still nothing particularly interesting happened, I thought... "all the reviews say this book is excellent, maybe the finale will make it all worth it". Nope, it did not satisfy.
There is one small highlight in this book, and it is Eleanor. She is a shy 31 year-old that spent the bulk of her life thus far caring for a demanding mother. She has only recently been free of this burden. The book centers a lot on her inner thoughts and it is both charming and touching. Anybody who has ever fought internal anxiety would be moved.
I was expecting some creepiness and bizarre, and I did not find any of that. Outside of Dr. Montague, the motives for any of the guests to bother coming were not made clear. Score: 2/5. If it wasn't for the book's strong reputation, and the fact it was a fairly short novel, I likely would have given up on it.