Twelve-year-old Evie Beaulieu sinks to the bottom of a swimming pool in Montreal strapped to one of the world's first aqualungs. Ina Aroita grows up on naval bases across the Pacific with art as her only home. Two polar opposites at an elite Chicago high school bond over a three-thousand-year-old board game; Rafi Young will get lost in literature, while Todd Keane's work will lead to a startling AI breakthrough. They meet on the history-scarred island of Makatea in French Polynesia, whose deposits of phosphorus once helped to feed the world. Now the tiny atoll has been chosen for humanity's next adventure: a plan to send floating, autonomous cities out onto the open sea. But first, the island's residents must vote to greenlight the project or turn the seasteaders away.