A sequel to Saturn's Children, Neptune's Brood takes place in the far future, following Krina, a mendicant scholar as she tries to locate her sibling Ana who has gone missing on the water world of Shin Tethys, light years from New California, Krina's home. What follows is a tale of finance, fraud, piracy and plunder. Stross uses the novel not only to explore the problems of the humans in space but also to cock a snook at a great deal of the internet. As a result there are jokes about piracy, memes and internet mannerisms. Marrying this attitude with a clever plot, Neptune's Brood is a pacey, read more interested in balance sheets than blasters.
The novel in part addresses one of the author's obsession with how unlikely human colonisation of space is. As a weak and fleshy species the hard vacuum of space is probably an environment that humans will not prosper in. As a result, these novels feature robots who are not only autonomous, suited to life in hard vacuum; but also have their programming modelled on human brain patterns, making them our species true children. Stross extends his doubts about popular SF tropes to FTL travel within the pages of Neptune's Brood, fingering it as a source of fraud across settled space and bringing it into the novel and Krina's world, by tying it intimately to the plot.
There is a great deal about finance in the book, and Stross uses the subject to examine not only the way financiers can become corrupt, but also to play with ideas; creating the concept of slow money, which exists purely for the purpose of space colonisation and is worth so much that it underpins entire star systems.
Stross' style here veers between a chatty diary and an almost naive approach, a voice that captures Krina's character well. He puts in phrases that are reminiscent of Literature in places, often twisting it for comedic effect. We get the impression that Krina is rather bookish and naive and this give her a charming aspect for most of the book, as well as allowing Stross to insert infodumps to explain his concepts: yielding to her tendency to explain things to give the reader important information. This feels clumsy in places, but it does at least fit the character and never truly impedes the plot.
Krina is a strange character, however. She feels unsuited to adventuring and in many ways, the events of the book happen to her rather than her instigating them. Trouble finds her, not the other way around. This is in stark contrast with most of the other characters, who are grifters, scammers and conmen: beautifully drawn and far more dangerous. We meet communist squid, a piratical a-Count-ant, a set of priests who are determined to achieve the impossible and many, many mermaids. Even Ana, who obviously means well has more agency than Krina, and I suspect the only reason Krina doesn't feel like a pale figure in comparison to the rest of Stross' menagerie is because she is our protagonist.
On the whole though, this is a good novel, reflecting the current world and the complexities of the finance system.