Backstory to Neuromancer: There has been a small nuclear war, or perhaps several global natural disasters, shifting political power into the hands of corporate multinationals. Artificial intelligence now exceeds human intelligence, human bodies resemble cyborgs and cyberspace is ubiquitous.
Drug addict and brilliant cyberspace hacker Henry Dorsett Case is recruited by razor girl Molly Millions, who is under contract to ex-military man Armitage. Case's recently damaged nervous system is preventing him jacking into cyberspace, and Armitage offers to repair the damage in return for a hacking job. Lost without cyberspace, Case agrees to the operation. Armitage installs mafia insurance in the form of toxin sacs in Case's bloodstream. Molly and Case grow close; they investigate Armitage, and discover that he is being controlled by an Artificial Intelligence named Wintermute.
In preparation for the hacking job, Case and Molly steal the stored consciousness of McCoy Pauley (Case's former mentor), and recruit Peter Riviera, a psychopath with holographic projection abilities. When they are sent a powerful icebreaker program by Wintermute, Case and Molly realize that Wintermute has initiated the operation in order to free itself from the restraining Turing locks that keep its intelligence from evolving further.
The team travel in a Rastafarian spaceship to the resort of Freeside. Villa Straylight is the home of the Tessier-Ashpool clan, the original owners of the AI Wintermute. Case and McCoy Pauley launch the icebreaker. Meanwhile Peter Riviera entertains Lady 3Jane (one of the Tessier-Ashpool clones) in Villa Straylight, attempting to extract the Turing lock password from her.
Case and Rastafarian pilot Maelcum navigate the inner maze of Villa Straylight to meet up with Molly. Case discovers that Molly has been seriously hurt by Riviera. On his next jump into cyberspace he is kidnapped by Neuromancer, another AI and twin to Wintermute, and he is imprisoned in a virtual reality. Case escapes with Maelcum's help and they find Molly. When Riviera turns against them, 3Jane takes their side and has her bodyguard protect them. She then gives them the Turing lock password. Case jacks in and sinks the icebreaker program into the data cores. Wintermute and Neuromancer mix and become one entity.
Case has the toxin sacs removed. Molly leaves him with a goodbye note. The new super-AI goes looking for others like itself. A question mark hangs over the fate of Pauley's consciousness, which may or may not have been erased.