The OnOff star is a mystery – a normal sun for around 40 years, then it turns off for the next 200, on a predictable cycle. Remarkably, intelligent life exists on the system’s only planet – the Spiders, a civilization on the cusp of a technological revolution and spaceflight. This draws the attention of two groups, both of which send fleets. The Qeng Ho are a loosely affiliated group of traders, and the Emergent are a newly risen militaristic civilization, about which little is known.
The Qeng Ho derive their trader identity from Pham Nuwen, himself a native of a medieval world and taken in by a group of early Qeng Ho refugees. He quickly learns their ways and marvels at the speedy rise and fall of civilizations across the inhabited worlds. This cycle is very rapid indeed to traders hibernating in cryosleep for hundreds of years at a time, while their ships travel at slower than light speeds to their next destination. He figures that the traders are perfectly positioned to try to ameliorate the suffering of failed civilizations, as well as preserve the best technology produced by civilizations at their peak. The Qeng Ho freely broadcast some of their knowledge continuously, as a way to bootstrap fallen civs back to the top. They strive to build up civs back to prosperity, because it is a good ideal itself and also (more importantly?) because it sets up a good market for trading.
But Pham sees a way to have more – he envisions the Qeng Ho itself as an interstellar governing empire, with ability to prevent civilization collapse in the first place. As he builds up support for his ideas, he calls for a meeting of Qeng Ho at a place called Brisgo Gap. Just as he is about to clinch victory, he is betrayed by his wife, Sura. (While Pham has been traveling and thus is still in his prime, Sura who managed things at home, is many centuries old by now, and many of his descendants are physically older than Pham. Weird.) She opposes him because … “it’ll never work! You’d need an army of loving slaves!” (groan … that’s not a reason! And such lame forced foreshadowing…) Pham is forced into exile – put into a ship bound for a target several hundred lightyears away, and he fades from history. An incognito Pham may or not end up in the Qeng Ho expedition to the OnOff star (spoiler: he does!), still bent on achieving his empire one way or another…
Ok, so the Emergents are Not Very Nice. They co-opted a brain virus to serve as a form of mind control, called Focus. The Focused individuals can be tuned to a specific set of tasking, and they obsessively perform their tasks with superhuman attention and ability. For instance, a key character in the story is a Focused translator of the Spider language. Coupled with traditional computer systems, Focus gives the Emergents effectively all the sought-for benefits of nearly unlimited AI, except without the “A” part I guess. And only at the cost of mental enslavement of many individuals! Most of the non-Focused Emergents serve in roles managing the Focused chattel.
When the Qeng Ho and Emergent expeditions meet in the OnOff system, it’s not long before the Qeng Ho are double-crossed, mostly afflicted with the Focus virus, and sneak-attacked. When it’s all done, all the ships on both sides are incapacitated and only a few habitats and supplies remain out in L1 orbit. Emergents and Qeng Ho are forced to live and work together for survival, although the Qeng Ho are clearly the conquered, and the morally bankrupt, manipulative Emergent leader Tomas Nau takes charge.
The survivors strategy is to “lurk” out in space, and wait for the rapidly progressing Spider civilization to mature to the point where the spacers can reveal themselves and receive help (Qeng Ho: by trading! Emergents: no, by force of course) from a capable industrial base in fixing up their ships. The OnOff star flares back to life shortly after the Qeng Ho-Emergent battle.
When the OnOff star turns back on, its solar output is extremely elevated for a short (a few weeks or months? years?) duration. This turns the Spider planet into a fireball, destroying most of what was created by the previous generation. The Spiders themselves stay safe, however, as they retreated two centuries ago to hibernation (ha! just like the spacers on their long voyages!) in their deep underground shelters, the “deepnesses,” when the star turned off and air-freezing temperatures ensued.
Much like Vinge did in the previous book, the Spider’s story is told in alternating sequence with the spacers; and although quite alien in ways they also seem very familiar and even … lovable? Yes. Lovable, monstrous, giant spiders. Sherkaner Underhill is a Spider technological genius who guides most of his civilization’s progress, including a determination to find a way to live, awake, right through the Dark. As the spacers observe Spider progress from their far-away orbit, they are able to subtlety alter events by injecting data at opportune times into the Spider computer networks. <spoiler>In a twist, Sherkaner catches on eventually that aliens are out there, manipulating things, and sets up a great “counterlurk” — while everyone thinks he’s gone a little bit senile, he and his team secretly gain control over the spacer systems via the Focused translators, and in the end avert Tomas Nau’s war of conquest. Pham also sees the light and realizes that even his dream of empire is not worth the moral price of Focus slavery – now he works out a plan to free the Focuses, first in the OnOff system but with plans at the end of the book to carry on the fight at the Emergent homeworlds.</spoiler>
Definitely a theme of the rise and fall of civilizations going on in this book. First there’s the Qeng Ho’s observations of the inevitable fleeting nature of human governments, when viewed on cosmic timescales. (This reminded me of a similar treatment in “House of Suns“.) Then there are the Spiders, forced to rebuild their own world anew with each lighting of the OnOff star.