Sequel to Barnes’s far-future A Million Open Doors (1992), set a millennium hence at a time when Earth’s scattered colonies, long isolated by the vastness of interstellar distances, are reestablishing contact via the newly invented “springer” or instantaneous transporter. Mysterious spymaster Shan of the Council of Humanity’s Office of Special Projects sends expert diplomat/agents Giraut and Margaret Leones to assess the potentially violent situation developing on the remote and only recently recontacted planet Briand. Only Briand’s antarctic continent, projecting above the hot, poisonous chemical-soup atmosphere, is habitable, and here, in mutual loathing, suspicion, and disagreement, exist two colonies, one derived from pre-Columbian Maya, the other comprising mystical Tamil poets. Equally problematic, the diplomats’ marriage is suffering a meltdown: Giraut rues his vanished swashbuckling youth, while plain-Jane Margaret feels unattractive and unwanted. Can Giraut and Margaret persuade the Tamils and the Maya not to slaughter one another, and patch up their tottering marriage? Despite the top-heavy multiple-culture backdrop, this is an intelligent, well-researched, adroitly handled and absorbing cultural clash with a notably surprising conclusion.