A Scanner Darkly

A Scanner Darkly is a science fiction novel by the American writer Philip K. Dick, published in 1977. The semi-autobiographical story is set in a dystopian Orange County, California, in the then-future of June 1994. The setting is Orange County in a 1994 that the book treats as near enough to the present for its drug economy to look ordinary.

The plot is built on a divided identity. Bob Arctor belongs to a household of drug users and is also an undercover agent whose assignment is to observe that household, and he shields his identity from the people he lives with, which becomes progressively harder to maintain as the novel's central substance takes effect. Arctor's undercover name is Fred, and the novel's drug of choice is Substance D, so the two lives cannot be kept apart for long: the surveillance equipment he uses is trained on the house he lives in.

The book is one of Dick's best-known works and served as the basis for a film directed by Richard Linklater in 2006. Its dedication and afterword list people the author knew who were damaged by drugs, which is why the novel is read as testimony as well as fiction.