|Author||Iain M. Banks|
The novel explores the Culture's response to an Outside Context Problem (OCP), with particular regard to Mind Incident Groups such as the Interesting Times Gang. As different groups both within and outwith the Culture vie for control of the OCP, Banks explores the moral dilemmas presented to a galactic superpower facing its potential destruction.
The Excession of the title is a perfect black-body sphere that appears mysteriously on the edge of Culture space, appearing to be older than the Universe itself. The artefact resists the attempts of the Culture and technologically equivalent societies (notably the Zetetic Elench) to probe it. The Interesting Times Gang (ITG), an informal group of Minds loosely connected with Special Circumstances, try to manage the Culture's response to the Excession. The Affront, a rapidly expanding race named for its systematic sadism towards subject species and its own females and junior males, also try to exploit the Excession by infiltrating a store of mothballed Culture warships and using them to claim control of the mysterious object.
The Sleeper Service, an Eccentric GSV, is instructed to head to the location of the Excession by the ITG. As a condition the Sleeper Service demands that Genar-Hofoen, a human member of Contact, attend it to seek a resolution with his ex-lover, Dajeil Gelian, who is the final human passenger on the GSV. They had had an intense love-affair and, after a series of sex changes, had each become impregnated by the other until Genar-Hofoen was unfaithful and Dajeil attacked Genar-Hofoen, killing the unborn child. Dajeil then suspended her pregnancy and withdrew from society for 40 years, and the Sleeper Service hopes to effect a reconciliation between them.
As the stolen Affront fleet approaches the Excession, the Sleeper Service deploys a secret fleet of 80,000 remote controlled warships, neutralizing the threat. It transpires that the Affront have been manipulated into their grab for power by members of the ITG who thought it was morally imperative to curb the Affront's cruelty by any means, and intend to use the Affront's theft of Culture warships as an excuse for war. The Excession releases a wave of destructive energy towards the Sleeper Service. In desperation, the Sleeper Service transmits a complete copy of its personality, its "mind-state", into the Excession, including its knowledge of the conspiracy that has the effect of halting the attack. The Excession then vanishes as mysteriously as it appeared and the brief war with the Affront is halted.
During these events, and after speaking with Genar-Hofoen, Dajeil decides to complete her pregnancy and remain on the Sleeper Service, which sets course for a distant Galaxy. Genar-Hofoen returns to the Affront, having been rewarded by being physically transformed into a member of the Affront species (whose company he finds more stimulating than that of the Culture's people).
The book's epilogue reveals that the Excession is a sentient entity that was acting as a bridge for a procession of beings that travel between universes. It also assesses whether the species and societies it encounters are suitable to be enlightened about some unknown further existence beyond the Universe; as a result of events in the story the Excession concludes that the civilisations it has encountered in this universe are not yet ready for enlightenment. It also takes the name given to it by the Culture – The Excession – as its own.
Amorphia - Avatar of the GSV Sleeper Service
Dajiel Gelian - passenger on the GSV Sleeper Service
Genar Hofoen - Culture Agent
To be Added