Ah, Culture what would SF be without you? Probably vastly poorer and leaving us without suitable similes for things like Asher's Polity series.
Anyway, this is a Culture novel that has multiple strains of narrative, somewhat inter-related (even if it's not always that obvious). It is also a story about love, about sorrow, what constitutes good and evil. And possibly slightly about the responsibilities you have as a civilisation, for your past and future actions.
One strand is a composer, who's of a race of predators (the Chelgrsomethings), but who has now solidly decided that his former home memetope is no longer for him at all and has emigrated to a Culture Orbital.
Another strand is a Culture anthropologist/biologist/something who's way out in a weird "I am made entirely of gas" planet but not really a gas giant (ultratech, weirds everything, you know).
A third strand is a Chelsomething military, on a secret mission. A mission so secret that not even he knows what it is.
And then stuffs happen, in unimitable Banksian style. Possibly not the best first introduction to The Culture (mine was Player of Games, then Excession if memory serves me right), but probably not the worst possible.