This is the second book in a four book series.
A Deepness in the Sky (Prequel)
After the Battle on Starship Hill (Prologue to The Children of the Sky)
Long after the human race has ventured into the stars mankind is still an unstable species. Civilizations grow and flourish on many worlds, but all eventually crumble only to be rebuilt again.
When the first intelligent alien species is discovered two human factions send missions to make first contact. The aliens, dubbed Spiders by the humans because of their appearance, live on a planet with a bizarre sun that only shines for 35 out of every 250 years. The spiders spend the intervening 215 years in hibernation. The humans arrive just before the end of one of these hibernation periods.
The Qeng Ho trader faction led by Pham Nuwen who also appears in A Fire Upon the Deep, operate a trading network throughout human space. The Emergent faction use a unique form of mind control to enslave those they need to achieve their ends. Whoever succeeds in forming a trade deal with the Spiders will benefit hugely.
With such a prize on offer, treachery triggers a war between the two factions which nearly kills them all. The survivors are forced to unite under the domination of the Emergent’s and begin manipulating the spiders development until they reach a level of technology where they can repair the human ships.
But some of the spiders have become aware of the human ships high above, and have plans to free themselves.