A Fire upon the Deep tells the story of the Perversions attack on civilization and of the countermeasures taken against it. The Perversion is unwittingly unleashed by an advanced society, but the process also produces a countermeasure. As the Perversion advances, the unusual crew of the spaceship Out of Band II races to activate and guide the countermeasure. They succeed, and the galaxy is saved, although a substantial piece of high civilization has been set back for some period of time.
In the environment of A Fire upon the Deep, shells of potential, shaped roughly like a childs toy top, define activity in the Milky Way. Even thought cannot exist in the central Unthinking Depths. The closer that sentients approach this limit, the less intelligent they become. The next shell out defines the Slow Zone, where any information transfer is constrained by the speed of light. The outermost boundary separates the Beyond, where advanced civilizations dwell, from the Transcend, where the Powers dwell.
On a planet barely inside the Transcend, the Straumli Realm accidentally unleashes a great evil power, the Perversion. As researchers escape their laboratory, they take with them a countermeasure to the Perversion. This countermeasure lands on Tines World, very near the Slow Zone. As they emerge from their ship, the humans are massacred by large, somewhat doglike creatures with a pack intelligence requiring at least four members....
(The entire section is 474 words.)