In the post apocalyptic world of Leech, doctors (along with all other medical personnel) have been groomed into a single entity, the Institute, with many bodies/doctors who can be directed in the goal of keeping humanity from further destroying themselves (and also in furthering the goals of the Institute, though they like to keep that part under wraps). When one of the bodies suddenly dies with no explanation, a new doctor is sent out to a remote chateau to investigate how this could have happened without the knowledge of the Institute. What that doctor finds in the chateau will challenge the control of the Institute in a way it didn't consider possible.

I've always been intrigued by the idea of hive mind creatures in sci-fi and horror so I'll admit that I was initially very intrigued by Leech, an interest which was only stoked further when I heard the comparisons to one of my favorite movies, The Thing. After finishing it, I can definitely put this in the same boat as The Locked Tomb in terms of being a story which is very much my kind of book but that is likely to be very hit or miss for others.

Leech, by nature of its exploration of a hive mind under threat in a very dystopian world, explores a lot of interesting ideas around responsibility, autonomy and identity. It takes ideas from The Thing about the horror of someone potentially not being who they appear to be and accelerates that by having a very isolated atmosphere where tension and dread is built slowly as the doctor investigates. It has a very wintery feel that makes it perfect for the season and I would definitely consider it more horror than sci-fi as it delves pretty strongly into body horror and a few other content warnings that I'll mention in spoilers child abuse, sexual assault. And as you often get in a dystopian world, it's as much about the horrors of what people do to each other as to what the dangerous creatures of the world do to them.

I suspect that the writing style is going to be the real sticking point for folks since it's fairly dense, formal and a bit removed so it probably won't work as well for readers who are heavily character driven. There are some interesting character arcs but because you're dealing with a hive mind, you don't see as much of an individual personality.

It took me a little while to get into the style of the story, I ended up switching to audio around 15% in and that helped me get used to it enough to build more intrigue. Additionally, there's a French language influence in the book and one of the minor characters in particular has a very thick French accent both in the audio and in the actual dialogue in the book that might be a little tougher to parse without some familiarity with the language. I didn't mind that but I have seen complaints about it in the reviews for the audiobook.

Overall, I'd recommend Leech to readers who enjoy a story like The Thing, where the atmosphere is very cold and isolated, dread is built slowly as the characters begin to learn about what threatens them and body horror is fairly present throughout. While it took me a little bit to get into, I ended up being completely sucked into this world, with its intriguing mix of sci-fi, horror and supernatural elements and I'm rounding up from a 4.5 to 5 for Goodreads. I'll be very interested in whatever Ennes writes next because I think they did an excellent job here of exploring a concept I don't see often and hit exactly the vibes I want from my sci-fi/horror sub-genre.