In A Scanner Darkly, Les is a narcotics officer working undercover in a drug-ravaged futuristic society. He becomes addicted to Substance D, a powerful and highly addictive drug, while trying to infiltrate a drug syndicate. The drug has powerful hallucinogenic effects, causing Les to lose touch with reality and even his own identity.
As Les struggles with his addiction and deteriorating mental state, his relationships with his colleagues, including Natalie, become strained. Natalie, who has her own secrets and struggles with addiction, tries to support Les but also feels overwhelmed by his erratic behavior.
Throughout the film, the lines between reality and hallucination blur as Les grapples with his drug-induced delusions and paranoia. As he becomes more isolated and paranoid, he starts to question the motives of those around him and begins to suspect that he is being monitored by the government.
Ultimately, A Scanner Darkly is a dark and complex exploration of addiction, identity, and surveillance in a dystopian world where reality is constantly shifting and nothing is as it seems.