Excession by Iain M. Banks

First published in 1996; published by Orbit on January 20, 2026

Long before AI became a media-dominant thing, Iain M. Banks was writing about a future shared by humans and a civilization of AI known as the Culture. Members of the Culture take the form of space-faring ships and, no less than humans but at much faster speeds, quarrel about moral behavior and their individual places in the universe.

Banks (who sans the middle initial, also wrote worthwhile mainstream novels) died in 2013, leaving behind nine novels and a collection of short stories in the Culture universe. Excession is the fifth in the series. Because it is one of the few I missed, I was pleased to see that Orbit is rereleasing the novel in paperback and ebook editions.

The story begins with Dajeil Gelian confined in a tower overlooking a hologram of a sea that is housed in a ship named Sleeper Service. Dajeil shares her prison with a black bird named Gravious. Dajeil is pregnant and, we eventually learn, has been in that condition for decades. The ship’s avatar notifies Dajeil that it finally has a mission and will be leaving its guests (most either bodies in suspended animation or existing as stored data) in appropriate habitats.

The mission involves the Excession, an alien entity or artifact that is connected to the energy grids that exist above and below the universe. Nobody known to the Culture has ever seen anything like it. It seems to be older than the universe itself; its ability to connect to the energy grids is astonishing. When a Culture offshoot, the Elench, stumbles upon it and investigates, the Elench ship is taken over. A drone manages to escape the ship but is soon destroyed, leaving behind a small but detectable (if another ship knows where to look) debris field.

Special Circumstances (the “espionage and dirty tricks department” of the Culture’s Contact section) recruits Byr Genar-Hofoen to perform a secret task that indirectly pertains to the Excession. Byr is currently a human ambassador to a war-prone alien race called the Affront. Special Circumstances arranges his transportation on an Affront vessel to a Culture ship that will rendezvous with Sleeper Service. It turns out that Byr and Dajeil have a history.

Much of the novel involves real and suspected conspiracies among various Culture ships that relate to the Excession. Some Culture ships want to manage contact with the Excession; others want to confront it. The Affront concoct a scheme to control some old Culture warships in an effort to claim the Excession for their own purposes. Chaos ensues.

The novel includes a story within a story that becomes the main story, focused on Byr’s troubled relationship with Dajiel. Most of this is told by way of backstory. No fan of monogamy, Byr nevertheless made a quasi commitment to Dajiel by changing himself into a woman (the process takes about a year in the far future but no surgery is required) so that both can become pregnant with the other’s child (no penetration needed, although Byr in male form is a big fan of penetration). Jealousy ensues when Byr, in female form, canoodles with another woman.

Excession is far from my favorite Culture novel but the universe Banks created is so intricate and interesting that I always enjoy paying it a visit. The few human characters behave like humans (i.e., they are messy) while the ships send wonderfully snarky messages to each other. The potential war between the Culture and Affront, as well as the potential conflict with the Excession, resolve in a way that might be criticized as predictable, but the process of getting to that point is more than half the fun. While the story is lengthy and occasionally bogs down, I have to recommend it to Culture fans.

Newcomers to the series should probably start with the first novel, Consider Phlebas, to gain context that will aid appreciation of the others. Consider Phlebas is also one of the best in the series. Culture completists should nevertheless add Excession to their Banks collection if they haven't already.

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