Banks pulls out all the stops in this gloriously over-the-top, state-of-the-art space opera, a Hugo nominee in its British edition. In a galaxy teeming with intelligent life-forms and dominated by the intensely hierarchical society known as the Mercatoria, the Ulubis system has been cut off from the rest of civilization for over a century as its citizens impatiently await the arrival of a starship carrying an artificial wormhole to replace one destroyed in a previous war. Fassin Taak is a Slow Seer, an anthropologist who studies the Dwellers, the ancient, enigmatic species that inhabits gas giants throughout the galaxy, including Nasqueron in the Ulubis system. Fassin's research contains clues to the existence of a secret wormhole network, one operated by the Dwellers and free from the repressive control of the Mercatoria. Unfortunately, the monstrous ruler of a nearby star system has also learned of this discovery, as has the Mercatoria itself. Now two enormous battle fleets converge on Ulubis, and Fassin must undertake a quest deep into Nasqueron to uncover the Dwellers' secret. This is an enormously enjoyable book, full of wonderful aliens, a sense of wonder and subtle political commentary on current events.