After the fall of Damascus, the surviving octopuses in orbit barely avoid extinction. They expand aggressively into a tangled habitat network using automated miners, but their society remains unstable, quarrelsome, and factionalized. Noah, a male scientist-artist haunted by visions of his species dying out, joins two similarly far-sighted females, Ruth and Abigail, because all three want to work beyond the short-term chaos of orbital society.

The trio leaves for forbidden Nod orbit. Ruth and Abigail want to study the organism that devastated Damascus and eventually cure or vaccinate their species so they can reclaim the planet. Noah has a different goal: he has given up on Damascus and wants escape, using old human records, star maps, and lost engineering knowledge from the abandoned station to pursue a radical new technology.

They dock with and reinforce the dead orbital station, converting parts of it for aquatic habitation and rigorous quarantine. Drones observe Nod’s seas, locate the remains of the old habitat, and bring up samples from the salt marsh biome, including host creatures carrying the alien colonial organism. As Ruth and Abigail experiment on the infection, Noah builds a strange exterior device based on old human theories and octopus advances, hoping to solve the problem of interstellar distance.

Noah keeps partial quarantine between his work and the females’ laboratories, but he notices when Ruth and Abigail retrieve something much larger from Nod. The object or being has a deeply familiar, humanity-associated shape, and the females shift from epidemiology to communication while keeping the discovery hidden. Soon afterward, a hostile octopus faction from Damascus orbit arrives, judging the Nod research an unacceptable violation of taboo.

Ruth and Abigail try to negotiate with the armed ship, showing their scientific rationale and hopes of saving Damascus while concealing the new subject. When persuasion fails, the station’s defensive fields bend lasers, confuse missiles, and misdirect fighters, which only convinces the attackers that the station must be destroyed. The warship fires railgun projectiles that the station cannot survive.

Facing death, Noah activates his unfinished device in rage and self-defense. The warship and nearby fighters vanish before their projectiles strike, apparently reduced to a thin scatter of atoms stretched toward a star system seven light years away. Noah dies satisfied by the successful test, and then the railgun rounds tear through the station, killing the trio and leaving the site as an unquiet tomb for future visitors.