Sequel, of sorts, or at least the first Culture novel to directly refer back to the Idiran War which was, of course, the backdrop of Consider Phlebas. An elaborate, intricate, carefully compartmentliased plot against the Culture is being carried out by a suicidal agent from a planet that was victim to one of Special Circumstances more disastrous interventions. Meanwhile, the Mind of an Orbital prepares to mark the arrival of the light from twin supernovae set off as part of one of the final actions in the Idiran War with an orchestral composition by an self-exiled composer from the same planet. Out on the rim of the galaxy a scientist studying an ancient alien species glimpses a dark shadow in the depths of the floating world. It all comes together in a mix of grand spectacle and muted contemplation of guilt, death, lost love and atonement. Wasn't sure about the reader of the audio book at first, but as soon as he started doing the voices and handling the dialogue I could see why he was a good choice.