Convergence

Convergence is the eighteenth book in C.J. Cherryh's beloved Foreigner space opera series.
Convergence marks a new phase in the Foreigner Universe: knowledge about the dangerous situation in adjacent space rests only with Bren Cameron, the human diplomat to the alien court of the atevi, four starship captains, and the two chiefs of state—both the human and the atevi, who share the planet.
Bren is obliged to carry the just-signed treaty to the human government on an island some forty miles off the shores of the atevi-ruled megacontinent, and—without explaining the dire situation that would send the people into chaos—to arrange for the human refugees who are crowding the space station to be landed on the island, since the atevi will not grant more land to the human residents of their planet. Bren, a native of this island, is now an atevi official—trying to prepare the human inhabitants for the arrival of many more desperate human refugees from space.