A Scanner Darkly is a science fiction story that reflects the harsh realities of 1970s drug culture. In the novel, undercover cop Bob Arctor takes the illegal drug Substance D in order to pass as a dealer; however, one of the drug's side effects is a split in the two hemispheres of the brain, so Bob quickly loses his grasp on his two identities and two realities. The book delves into the theme of inner versus outer identity and examines the theme of sacrifice for the greater good.
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