Sarl is a barely industrial backwater on the Eighth level of a Shellworld, a vast artificial planet of concentric levels. King Hausk is secretly murdered after a battle by his top aide, tyl Loesp. His oldest son, Ferbin the fop, witnesses the murder and flees for his life. Meanwhile, his sister Djan, who has long been a Special Circumstances operative in the Culture, hears of the death halfway across the galaxy and heads for home. Their younger brother, Oramen, is still a minor and so tyl Loesp becomes the Regent.
It turns out that there’s much more at stake than regicide in a primitive society. Banks moves the narrative back and forth across several levels of societal advancement, from Sarl at the bottom to the High-Level Involved like the Culture at the top of the food chain. He examines the bloody futility of war, personal heroism, (literal) world building, and an aeons-old evil, weaving them together in a well-crafted tale.