Warning: Wikipedia contains spoilers.
Based on the ideas in the book Future Shock by Alvin Toffler, the novel shows a dystopian early 21st century America dominated by computer networks, and is considered by some critics to be an early ancestor of the "cyberpunk" genre. The hero, Nick Halflinger, is a runaway from a government program intended to find, educate and indoctrinate highly gifted children to ensure they pose no threat to the ever growing powers of the state. Nick gradually realises this, and growing more and more disenchanted, eventually goes on the run, using stolen computer access codes to cover his data trails and create new identities for himself.
The novel is set in the weeks following his recapture after several years on the run, alternating between moral aguments with his interrogator, who is trying to discover why the program's star pupil had absconded, and flashbacks of his career. The interrogator, a later graduate of the same program, gradually comes to realise that he has more sympathy with Nick's views than his employer's, and eventually absconds himself, giving Nick computer access so that Nick can make his own escape.
This time round, Nick has another plan, and rather than running and hiding, spends a number of months travelling the country, aided by an `invisible college' of academics that he's encountered, picking their brains for information and access codes, and steadily refining a program that he's loading onto the computer networks. (Brunner invented the term "worm" for this program, as a self-replicating program that propagates across a computer network - the term "worm" was later adopted by computer researchers as the name for this type of program.)
The worm is eventually activated, and the details of all the government's dark secrets (clandestine genetic experimentation that produces crippled children, bribes and kickbacks from corporations, concealed crimes of high public officials) now become accessible from anywhere on the network - in fact, those most affected by a particular crime of a government official are emailed with the full details. The book ends optimistically, with there being no more privileged hiding of information, no more secret conspiracies of the rich and powerful.