The Sanatorium, much in the same vein as One by One, takes place at a luxury resort in the Swiss Alps and is just as full of tensions and secrets. The resort itself has been converted from an old, closed sanatorium into this new, modern resort, and our main character Elin Warner has been invited to visit for her brother's engagement celebration. But someone goes missing, and another turns up dead, and things take a quick nosedive. And, just like in One by One, a snowstorm and avalanche eventually trap everyone together in the resort.
I enjoyed this one much less than One by One, and that was largely because I really didn't care for the main character and actually found myself somewhat annoyed with her actions and interactions with her fellow characters. I never felt like anyone really liked each other in this book, and I know that sounds like a dumb thing to say in a thriller like this, but there was no real connection between any characters and it made it hard for me to care about them, either. There was just something off about this entire story that I really didn't connect with or care for, and I found myself asking myself why I was reading this at a few too many moments.
I also felt as though the titular sanatorium element was sort of ignored except for when it was relevant, and I was a bit disappointed that this element wasn't utilized more or in a more creative manner. There were a lot of things that didn't work for me with this book, and the atmosphere didn't really give me that claustrophobic locked room vibe that I look for in books with similar premises. Because of that, I've given The Sanatorium 2.5 stars.