A ragbag collection of sociopaths are bioengineering to live and work in the deep ocean maintaining the geothermal energy plants on which the future world depends for its electricity. Apparently the mega-corporation who sent them down thinks their peculiar personalities makes them just right for the job. Needless to say there is a lot more going on down in the depths than anyone anticipated and what starts out as a story of dysfunctional humans living in extreme conditions turns out to have consequences which threaten all life as we know it. This is really superior sci-fi and a highly recommended read. It is only after finishing it that I realised it is the first part of a trilogy. Indeed this first volume was such a satisfying and complete read in itself that I think I may wait a while before tackling the follow on books.