"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...