Matter Matter is a science fiction novel from Iain Banks, under the name Iain M. Banks in his Culture series.

The book follows the experiences of three members of the royal household of the Sarl, a humanoid race living on the 8th level of the Shellworld of Sursamen. The Shellworld is an ancient artificial planet consisting of fourteen nested concentric spheres internally lit by tiny thermonuclear "stars", whose layers are inhabited by various races. The Oct, the mentoring species of the Sarl, meanwhile have been organizing the takeover of the 9th level of Sursamen, using the Sarl as their pawns.

In a world renowned within a galaxy full of wonders, a crime within a war. For one brother it means a desperate flight, and a search for the one - maybe two - people who could clear his name. For his brother it means a life lived under constant threat of treachery and murder. And for their sister, it means returning to a place she'd thought abandoned forever.

Only the sister is not what she once was; Djan Seriy Anaplian has become an agent of the Culture's Special Circumstances section, charged with high-level interference in civilisations throughout the greater galaxy.

Concealing her new identity - and her particular set of abilities - might be a dangerous strategy. In the world to which Anaplian returns, nothing is quite as it seems; and determining the appropriate level of interference in someone else’s war is never a simple matter.

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