[1] It is set more than 481 years after The Rise of Endymion; the Pax is long since defeated, and the Aenean movement has been helping various groups colonize unknown space.
Four of the five shipboard AI (apparently formerly of the TechnoCore; in characteristic Simmons fashion, each is patterned after a famous literary figure, in this case, Japanese: Saigyo, Lady Murasaki, Ikkyu, Basho, and Ryōkan) decide that the call is worth investigating, not least because of the further anomaly that the orbital forest around the lesser of the two stars, which the AIs intend to resupply their ship from, is of neither Ouster nor Templar construction, though they may have settled on it.
Since they cannot get to the system normally before the harvester strikes again, the crew votes to risk the Helix and its hundreds of thousands of stored inhabitants by making a very short Hawking drive jump.
It is honey-combed, and occupied by a curious oxygen-breathing race, whose primary method of technological communication is via modulated gravity waves (explaining the failure of previous attempts to contact the harvester).
They are devastated to learn of what they had done, and immediately transmit a gravitonic sequence which would reprogram the harvester (they offer further to commit collective suicide to atone for their crimes, but the Spectrum feels that this is not needed), as indeed it does.