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From the back matter:
As the Earth withers and dies, humanity discovers an alien artifact capable of generating massive amounts of breathable atmosphere, allowing them to migrate to three normally uninhabitable planets similar to their dying home. The Source is placed on a station far off the worlds where its gift can be directed to the three planets. Without cause, the gate to New World I begins to malfunction, threatening a massive evacuation and the possibility of a complete shutdown of all the gates. The engineers aboard the station find that the Source is not a mere machine. It lives just as they do, and it requires sustenance to continue living, to begin propagating an alien species long extinct. For the Source to live, however, people must die. Will the very thing that saved humanity ultimately be its demise?