Super Short Summary

In A Fire Upon the Deep by Vernor Vinge, an ambitious human civilization called Straumli Realm accidentally unleashes an ancient superintelligent power known as the Blight while exploring a data archive in the galaxy's Beyond Zone. The Blight begins to spread, forcing children from Straumli Realm to crash-land on a planet inhabited by group-minded dog-like creatures called Tines. This event sets off a series of efforts by various beings, including a constructed human agent named Pham Nuwen, to contain the Blight and protect the galaxy.