An experiment has gone wrong in a lab in the Nevada desert. A swarm of nanoparticles (micro-robots) has accidentally been released into the outside world. And they evolve into something entirely more dangerous than planned...
So far so good, it reads like a typical suspense thriller/horror book - something is out there to get us. We are outnumbered, all alone and isolated, weaker and we have to come up with a way to kill it before it gets too smart and kills us.... Nothing unexpected there. But it is really creepy, especially because it has one of those more or less open endings that you can interpret any way you wish.
Reminded me a lot of his "Andromeda Strain", although that still is my favourite Crichton novel to date.
