Sharrow, who narrowly survived the assassination of her mother when a child, joins up with her former combat team on a series of quests. The group locate a number of Antiquities -- including the Crownstar Addendum, one of the most valuable pieces of jewelry in the solar system, and the Universal Principles, an ancient book -- on the way to the final quest for the last Lazy Gun. When it is eventually discovered, it is guarded by an elaborate defence system incorporating a genetic key which Sharrow has to deactivate.
Sharrow encounters various political systems on her travels across Golter, which lends the book a lightly satirical tone in places. She also meets The Solipsists, a gang of pirate mercenaries on a hovercraft, who hold very unusual philosophical beliefs.
Like Consider Phlebas, Against a Dark Background gets a lot of its power from the treatment of the dynamics within a team. The carefully drawn characters arguably work better together in this book.
'The sky was full of darkness. There were planets and moons and the tiny feathery whorls of the dim nebulae, and they had themselves filled it with junk and traffic and the emblems of a thousand different languages, but they could not create the skies of a planet within a galaxy, and they could not ever hope, within any frame of likelihood they could envisage existing, to travel to anywhere beyond their own system, or the everywhere-meaningless gulf of space surrounding their own isolated and freakish star. For a distance that was never less than a million light years in any direction around it, Thrial - for all its flamboyant dispersion of vivifying power and its richly fertile crop of children planets - was an orphan.'
Another possible derivation for the title of this book could be a 1975 Ursula K. Le Guin essay, "Science Fiction and Mrs. Brown", which concludes:
'And I think science fiction is - well, no, not important, yet still worth talking about, because it is a promise of continued life for the imagination, a good tool, an enlargement of consciousness, a possible glimpse, against a vast dark background, of the very frail, very heroic figure of Mrs Brown.'