Excession

Excession is a science fiction novel by Iain M. Banks, published in 1996. It is the fourth book in the Culture series, a set of novels set in a post-scarcity utopian space society known as the Culture. The story centers on a mysterious and ancient artifact, the Excession, which appears in space near the fringe of the Culture's territory.

The Excession is a black-body sphere, seemingly impossibly old and technologically advanced, far beyond anything the Culture has ever encountered. Its sudden appearance triggers a complex and often covert response from the Culture, involving various Special Circumstances agents and military factions. The novel explores themes of artificial intelligence, the nature of consciousness, inter-civilizational contact, and the potential dangers of advanced technology.

The narrative is characterized by its intricate plot, multiple interwoven storylines, and a cast of diverse characters, including both humans and advanced AI. The Excession itself acts as a catalyst for revealing the internal politics, ambitions, and anxieties within the seemingly utopian Culture. Banks employs a distinctive narrative style, often shifting perspectives and timelines, to build suspense and explore the profound implications of confronting the unknown. The novel is a significant entry in the Culture series, expanding its universe and delving into darker, more complex aspects of its society.