 The L.A. of a not-too-distant future suffers a surge of drug abuse involving a new ultra-addictive and eventually brain-damaging substance simply named "D". Bob Arctor is an undercover narc leading a double life, dutifully reporting to his superiors while effectively having abandoned whatever normal existence he had for a "D" user/dealer career. But this schizophrenic situation and the drug-induced memory and concentration lapses put Bob under mounting stress.