The Hydrogen Sonata
Iain Banks
 The Gzilt, a civilisation that almost joined the Culture 10,000 years before the novel, have decided to sublime, having had a referendum on the subject and voted in favour of it. Within the novel it is stated that several things happen once a civilisation has made such a decision: strange objects called Presences appear, Scavenger species (less technologically advanced species wishing to claim the departing species' technology) arrive, and if any other civilisation has kept anything quiet with regard to that civilisation it is custom to reveal it to the subliming civilisation before they depart – a setting of the record straight for advanced civilisations. One such species, called the Zidhren, have quite a large secret. They planted the Book of Truth, which the Gzilt revere – and it is implied that the religion made the Gzilt refuse to join the Culture in the past. However, the Zidhren themselves have long since sublimed as a species, meaning the remaining Zidhren – the Zidhren-Remnant – are left to deliver the message. However, when they try to do so the Gzilt warship that meets them decides to keep it quiet, by destroying the Zidhren-Remnanter ship. Meanwhile The Culture has sent ships to both wish the Gzilt well, as they have always been on good terms with the Gzilt, and to keep an eye on the scavenger species arriving. The Mistake Not My Current State Of Joshing Gentle Peevishness For The Awesome And Terrible Majesty Of The Towering Seas Of Ire That Are Themselves The Milquetoast Shallows Fringing My Vast Oceans Of Wrath (called Mistake Not... for most of the book) – a ship whose name, classification and actions in the book suggest it is some sort of military berserker – has been assigned to meet the Liseiden, one such scavenger species, and notices the destruction of the Zidhren-Remnanter ship even though it is quite far away. Unfortunately for those who wish to keep the truth about the Book of Truth secret, the Gzilt warship had spyware implanted in it, which sent a message to the Gzilt 14th Regiment about the Book of Truth's truth. As a consequence of this, the 14th Regiment calls Lieutenant Commander Vyr Cossont out of reserve status. However, this spyware has been detected, and the Home Regiment of the Gzilt go to the Gzilt who effectively controls Gzilt civilisation, Banstegeyn, asking for permission to destroy the 14th Regiment, which he gives. It was also he who spearheaded the move for Gzilt civilisation to sublime, and does not want anything to stand in the way of the sublimation. Cossont is taken to the 14th Regiment's high command, and tasked with finding out if the Book of Truth really is a Zidhren plant. To do this, she must speak to the oldest Culture citizen still alive, one Ngaroe QiRia, who she has met before. Just before she can depart on this mission though the high command is attacked by the Home Regiment, Cossont narrowly escapes, and is picked up by the Mistake Not... Unfortunately, the same ship that destroyed the 14 Regiment's high command has also realised that Cossont has escaped, and pursues her. While she does make contact with Ngaroe Qiria, it turns out that he has wiped his mind of all memory of the Book of Truth, keeping one copy of the events coded into his eyes, which he has had amputated by an individual called Ximenyr who resides at an event called the Last Party, which has been going on for a number of years and will end when the Gzilt sublime. Cossont arrives at the Last Party and goes to where Ximenyr is staying, but the Colonel aboard the Gzilt warship following them takes a squad of robots (called Arbites by the Gzilt) with him and attacks the last party, causing many deaths. However Cossont still manages to recover the eyes, and the real truth about the Book of Truth is confirmed, but only to The Culture. After the Mistake Not... persuades the warship not to attack it, and to help the survivors of the Last Party, it confers with other Culture ships taking an interest in the Gzilt sublimation, and they decide to keep the truth about the Book of Truth secret. The time of the Gzilt sublimation then arrives, and most of the Gzilt sublime – some 99.99%. Cossont is one of the few that do not (for a sublimation to work, all of a species has to sublime within the same hour, and any biological trying to do so on its own will 'evaporate' into the realm of the sublime), and manages to finish what she was trying to do all along, which was play the eponymous Hydrogen Sonata, a challenging piece of atonal music.