A huge international corporation has developed a power facility at the bottom of the deep San Juan de Fuca Rift in the Pacific Ocean to exploit geothermal power. They have sent a bioengineered crew -- people who have been altered to withstand the pressure and breathe the seawater -- down to live and work in this weird, fertile undersea darkness. Unfortunately, the only people suitable for long-term employment at the bottom of the ocean in these experimental power stations are psychotic, some of them in unpleasant ways. But everything becomes a million times worse when a threat to all human life is discovered in the Rift, and none of the crew will ever be allowed to return to the surface. One of the central questions is how many of them can survive, or will be allowed to survive, long enough to become sane, while worldwide disaster approaches from below.