The series is set billions of years in the future of the Earth after the start of the Sun's expansion into a red giant has made the surface uninhabitable. It follows the lives of the two million survivors in the underwater city of Salus; its helmsmen, the Caine family; and its pirate enemies. The protagonists of the first issues are Stel Caine, who searches for life-supporting planets with robotic probes, her husband Johl, and their children. Remender summarized the story as being about "one woman's optimism in the face of inevitable and true doom".[1]
The first issues of the series received critical praise. In Paste magazine, Robert Tutton wrote of the "primal, silent awe" inspired by Tocchini's "surreal" and "dazzling" art.[2] In IGN, Tres Dean noted the creators' "complex and intriguing worldbuilding and precise, emotional character work", as well as Tocchini's "impeccable and breathtaking" art.[3]
