Tethys is a water world, home to floating city ships whose viability depend upon resources from Earth. So when the liner Leviathan explodes in orbit after factional fighting among passengers, the future of the planet looks bleak. Among those on the sole shuttle to escape the liner, however, are a number who might just make a difference. These include a marine biologist and her daughter, a military man seeking new opportunities, a businessman with a stolen template for a fantastical device, and a clutch of freedom fighters.
Amid rebellion, the construction of a seemingly useless machine, encounters with a belligerent new species, and the discovery of a rare earth deposit on the planet's sole landmass, the city ships compete to survive in this brave new world. Who wins - and how - will ultimately decide the fate of all on Tethys.