Algebraist - Iain M. Banks

It is 4034 AD. Humanity has made it to the stars but Fassin Taak, a Slow Seer at the Court of the Nasqueron Dwellers, will be fortunate if he makes it to the end of the year. The Nasqueron Dwellers inhabit a gas giant on the outskirts of the galaxy, in a system awaiting its wormhole connection to the rest of civilisation.In the meantime, they are dismissed as decadents living in a state of highly developed barbarism, hoarding data without order, hunting their own young and fighting pointless formal wars. Abruptly seconded to a military-religious order he's barely heard of - part of the baroque hierarchy of the Mercatoria, the latest galactic hegemony - Fassin Taak has to travel again amongst the Dwellers. He is in search of a secret hidden for half a billion years.But with each day that passes a war draws closer - a war that threatens to overwhelm everything and everyone he's ever known.