Off the coast of West Africa, decades after the dangerous rise of the Atlantic Ocean, the region's survivors live inside five partially submerged, kilometers-high towers originally created as a playground for the wealthy. Now the towers' most affluent rule from their lofty perch at the top while the rest are crammed into the dark, fetid floors below sea level.

There are also those who were left for dead in the Atlantic, only to be reawakened by an ancient power, and who seek vengeance on those who offered them up to the waves.

Three lives within the towers are pulled to the fore of this conflict: Yekini, an earnest, mid-level rookie analyst; Tuoyo, an undersea mechanic mourning a tremendous loss; and Ngozi, an egotistical bureaucrat from the highest levels of governance. They will need to work together if there is to be any hope of a future that is worth living--for everyone.