The fourth installation in Paul McAuley's cycle of novels following The Quiet War (2008), Evening's Empires is the best of the bunch so far. It's set roughly 500 years after the predecessor In The Mouth of The Whale (2012), placing it some 1500 years after the events of The Quiet War and Gardens of the Sun (2009). Like the two ﬁrst stories (but unlike the third), it takes place in our solar system.
A quick digression: I really need some name for that universe. I think calling it "The Quiet War Universe" both diminishes the later stories and misrepresents it; not only are there many historical events in the cycle that are at least as important as the Quiet War itself, the war is actually ancient history by the time the third and fourth novels take place.
One of the great things about the backdrop is that this universe feels lived-in. There's lots of interesting cultures (both human and posthuman), lots of interesting tech (the workings of which is often only sparsely detailed). There's very little classical Magitech (in particular, there's no faster-than-light travel), although there are lots of highly speculative technologies (personality uploading, a bewildering array of futuristic genetic engineering techniques, sentient AI, to name a few), most of which is concerned with creating novel post-humanities.
It has a big and complicated history, and Evening's Empires is full of little references to events both historical and contemporary, giving a distinct impression that the universe doesn't revolve around our POV character; he's just one of many people living in it. The other characters have their own lives, and from the various small insights we're given into them, they could easily have their own stories too. This is one of the things I've consistently liked about all McAuley's works, and is also one of the things I particularly enjoy about Alastair Reynolds' Revelation Space cycle and Iain M. Banks' Culture stories.
The historical backdrop has a distinct "late Dark Ages" feel. The True Empire (which feels sort of like an analogue of the Roman Empire) declined and fell, and a menagerie of both human and posthuman successor cultures have risen and fallen since. Rather than large nation-states, the predominant mode of social organization has become clans, small communes, city-states and religious conclaves. Intellectuals aren't as much making new discoveries as picking through the ruins of the fallen empire of yesteryear. I enjoy the fact that we've never actually seen the True Empire up close in any of the novels: The two ﬁrst novels are from long before the empire was established, the third deals with a remote True Empire colony, and the fourth is set after the empire collapsed. Again - this universe feels like it has an actual history.
Unlike the three earlier novels in this backdrop; this one has only a single POV character - the others had multiple separate POV characters, sometimes with only very little interaction between them. This, in my opinion, allowed it to rise above its already-impressive predecessors. This is not only another trip to a compelling and detailed future (as the three others): It's also the coming-of-age story of Gajananvihari Pilot, whose family was murdered and its spaceship hijacked immediately prior to the events of the novel. Hari is a great protagonist from a storytelling perspective: He has lived nearly his entire life on board his family spaceship, and his knowledge of the universe outside the family ship and business is about as limited as that of the reader (allowing the usual SF exposition dumps to take place in-character without breaking the story ﬂow). The story is also a quest for revenge and a scientific mystery (dealing with the aftermath of the events of In The Mouth of the Whale), and manages to blend space opera and hard SF in just the right proportions (in fact, this is largely why I love the works of both Paul McAuley and Alastair Reynolds so much). There's less hard science exposition than in the two ﬁrst books - possibly because much of the science in those dealt with biology, and McAuley himself is a biologist by education.
A minor nice touch: There's lots of references to other SF writers throughout, including at least Asimov, Clarke and Silverberg (which makes a lot of sense: Why wouldn't future space colonists pay homage to old science ﬁction authors they might have read once?). There's even a clever Tolkien reference near the end.
Easily my favourite installation in McAuley's series so far - and his is one of my favourite SF series to date, so that's high praise. Highly recommended.
An aside: McAuley has revealed that his next novel isn't set in this universe, but has also hinted that he will probably return to it later. I'm already looking forward to my next visit in it.