The Hydrogen Sonata

They are, truly, probably, the End Days for the Gzilt civilization. An ancient people, they helped set up the Culture ten thousand years earlier and were very nearly one of its founding societies, deciding not to join only at the last moment. Now they've made the collective decision to follow the well-trodden path of millions of other civilizations; they are going to Sublime, elevating themselves to a new a almost infinitely more rich and complex existence.

Amidst preparations though, the Regimental High Command is destroyed. Lieutenant Commander (reserve), Vyr Cossont, appears to have been involved, and she is now wanted - dead, not alive. Aided only by an ancient, reconditioned android and a suspicious Culture avatar, Cossont must complete her last mission given to her by the High Command - find the oldest person in the Culture, a man over 9,000 years old, who might have some idea what really happened all that time ago. Cossont must discover the truth before she's exiled from her people and her civilization forever - or just plain killed.