Dev Harmer, reluctant agent of Interstellar Security Solutions, has travelled to ocean world Robinson D, nicknamed Triton. Here, settlements belonging to the Terran Diaspora have been coming under attack by members of the planet's sub-aquatic indigenous race. ISS suspects the involvement of an agent provocateur working for humankind's galactic rivals, the artificial intelligence civilisation known as Polis+. As the violence escalates, Dev finds himself battling to restore order - but he has only seventy-two hours before his genetically engineered host form breaks down irreversibly. And all as an ancient god-beast rises from the depths to usher in an apocalypse...