Jack is a "did the right thing and got fired" tech fellow, who
specializes in writing code that mimics natural biological
behaviour. His wife is working with a company doing something with
nanotech. Things start to go wrong, and what escapes is nano-sized,
pred/prey programmed, and self-replicating. Each chapter ends with
slowly rising tension that I'm used to Crichton providing.
If I have any qualms, it's with the not-always explained abilities
of the escaped nanotech, and a somewhat obvious "this is what I
think is inevitable, so smarten up, humanity!" overtone that
Crichten might have toned down just a little.