From reading the other reviews of Annihilation, this seems to be one of those books which people either love beyond reason or are underwhelmed by and I've definitely fallen into the latter category more than the former. Not that it's a bad book and I certainly wanted to know what the hell was going on, not that I felt that I got any kind of resolution and, for me at least, that's one of the problems with it...
The basic premise of Annihilation, which is the first of a trilogy, is that there's a part of the world called Area X which is apparently encroaching on the rest very slowly and the folks of the Southern Reach have been sending expeditions in to find out what's going on. This requires some kind of hypnotism, as apparently it's impossible to cross over without it, and it's also unclear exactly how many expeditions have been sent even though none of them seem to have been either successful or to have survived unaffected. Partway through the book our main character finds a room full of journals which suggests hundreds of expeditions rather than the dozen or so she's been told about, but she's seriously losing the plot by that time so how reliable is her perspective anyway?
Yes, this is serious unreliable narrator territory, right from early on. There is 'something' living in an underground tunnel which is slowly writing post-apocalyptic ramblings on a wall going down into the earth, writing which turns out to be made of fungus and our protagonist breathes in some spores. From that point she begins to change, firstly in that she can no longer be controlled by the leader of their expedition who has been using hypnotic suggestion (the title of the book being one of them) to get her own way all the time. Anyway, bad things happen to the other expedition members and our hero (if she can be called that) starts to suspect that folks from other expeditions never really left Area X even though they supposedly returned home afterwards.
This was one of the points where things broke down a little for me, as our protagonist is pushed to join an expedition to find out what happened to her husband, a doctor on a previous expedition, but a lot of the time she seems quite flat as a character. Still, I read the entire thing even though it doesn't really have a resolution, and will probably read the next one (Authority) since my library has a copy.