Lifelong friends Basem, Mustafa, and Aarfah have carved out a place for themselves in their corner of Muqadas, where they dream of climbing from their place in the city's lowest level, above the limb-snatching, disease-infested waters, to the very top of their vertical city. Young inventors who've seen firsthand the havoc the Habar infection causes set out to dazzle the masses with their innovative prosthetics and escape the dangers of Lake Saha. When their inventions catch the eye of a scout who is on the hunt for new talent to bring to the higher tiers, their dreams are suddenly within reach. But as the wonders of the upper tiers enchant, Basem, Mustafa, and Aarfah begin to question why the bounty of Muqadas falls short of reaching Lake Saha's inhabitants. Behind the beauty of the city's upper tiers lies dark and dangerous secrets-ones that threaten not only everything they've worked for but everyone they love.