Neuromancer (William Gibson, 1984)

Case, is a cyber-freelancer, able to jack himself into computer-systems and experience cyberspace as a three dimensional reality. Case, however, tried to steal from one of his more dubious clients who subsequently infected him with a Russian mycotoxin, effectively rendering him incapable of cyberspace work and therefore unemployable. We therefore meet him, down on his luck, and mixing with some rather eccentric characters in a downtown bar in Japan.