With the "Hydrogen Sonata", Iain Banks has offered readers yet another superb addition to his ongoing "Culture" space opera series of novels. These are novels that are more than action-adventure space opera science fiction epics, but instead, fictional parables on describing the importance of doing good works, the philosophical blurring between good and evil and other notable issues on ethics and morality which, alas, are all too often absent in much of what passes for contemporary mainstream fiction, and, therefore, are important reasons why great works of science fiction like the ongoing "Culture" space opera series deserve as broad a readership as possible, especially when written by one of our foremost writers in the English language, Iain M. Banks, who is well known for writing important works of mainstream literary fiction like his debut novel - as Iain Banks - "The Wasp Factory". "The Hydrogen Sonata" gives readers much of the standard tropes found in the subgenre of space opera science fiction, such as compelling battles between opposing military starships and fast-paced chases between characters in a setting as miraculous as a gigantic dirigible. However, "The Hydrogen Sonata" should be seen as an exemplary fictional exploration of self determination, identity, and responsibility for one's own actions as seen through the eyes of his chief protagonist, Lieutenant Commander (Reserve) Vyr Cossont, a musician who is called unexpectedly back to duty by the Gzilt Regimental High Command to seek out the oldest person in the Culture, who was a participant in the negotiations that led to its founding over nine thousand years ago. She is called back to duty during the final days of Gzilt civilization, one of the founding civilizations of the Culture, when virtually the entire population is ready to embrace the Sublime, the shedding of their physical bodies in exchange for immortality in a transcendent form of existence, emulating other, other civilizations which have gone before them. Banks has conjured one of his most compelling protagonists to date, and especially, a heroine as remarkable as any crafted by the likes of Ursula Le Guin and William Gibson. If nothing else, with "The Hydrogen Sonata", Banks reaffirms the relevance of contemporary science fiction to current literature, in providing yet another epic tale that dares to raise important questions pertaining to identity, self determination and one's own sense of responsibility; questions which are often absent in much of contemporary Anglo-American literary fiction.