Look to Windward (Culture 6)

After an unsuccessful intervention into its politics by the Culture, the Chelgrian civilisation collapsed into a civil war which killed five billion Chelgrians. Some years later, a faction of Chelgrians plots revenge. Mahrai Ziller is a Chelgrian composer living in exile on a Culture Orbital; Major Quilan, a Chelgrian veteran, is sent to the Orbital, officially to persuade him to return.