Nou Occitan is a place where duels are fought with equal passion over insults and artistic views alike. Giraut—swordsman, troubador, lover—is a creature of this swashbuckling world, the most isolated of humanity's Thousand Cultures. But the winds of change have come to Nou Occitan. As the invention of the "springer"—instantaneous interstellar travel, at a price—spreads throughout the human galaxy, the stability and purity of no world, no matter how isolated, is safe. Nor can Giraut's life remain untouched. To his wonder, his is about to find himself made an ambassador to a different human world, a place strange beyond his wildest imaginings.

Welcome to the Thousand Cultures—in which humanity's hundreds of settled worlds are finally coming back together, via the recently invented technology of instantaneous travel. And in which Giraut and Margaret work as professional diplomats, helping to finesse the stresses and strains of so much abrupt new contact among wildly diverse cultures. Now, however, their task is to bring in the terrifyingly hostile world of Briand, a planet of broiling acid oceans whose only habitable portions are Greenland-sized subcontinents that project out of the abyssal heat of the planetary surface into it stratosphere. But Briand's physical hostility is nothing compared to the venom its two human cultures bear toward one another. Into this terrible world come Giraut and Margaret to try to do the right thing by the Cultures, by the inhabitants of Braind, and by one another.

The sequel to A Million Open Doors and Earth Made of Glass Special agent Giraut Leones, betrayed by his superior and closest friend, swore he would never work for the Office of Special Projects again—but now he must. A new movement on Earth seeks to use the recorded personalities of the dead as helpless virtual reality playthings, and to the worlds of the Thousand Cultures—where the reborn are accepted as normal citizens—it's a monstrous crime. If Giraut cannot stop Earth from ratifying its plans, the tenuous structure of interstellar human civilization will collapse. Complicating matters, Giraut's brain now hosts a second consciousness-the revived mind of his long-dead friend Raimbaut. Together, Giraut and Raimbaut must confront their shared past while struggling with a deadly present.

Giraut Leones, special agent for the human Thousand Cultures' shadowy Office of Special Plans, is turning fifty—and someone is trying to kill him. Giraut's had a long career; the number of entities that might want him dead is effectively limitless. But recently Giraut was approached by the Lost Legion, an Occitan underground linked to an alliance of illegally human-settled worlds beyond the frontier. Also, it turns out that the Lost Legion colony has a "psypyx" —a consciousness-recording—of Shan, onetime boss of the Office of Special Plans. If they have that, they have literally thousands of devastating secrets. Now, returning to his native Nou Occitan, Giraut will encounter violence and treachery from human and artificial consciousnesses alike. As bigotry and mob violence erupt throughout the rapidly destabilizing interstellar situation, Giraut will be called on the make the ultimate sacrifice, for the sake of civilization itself…