Do Androids Dream of Electric Sheep?

Filmed as Blade Runner, Do Androids Dream of Electric Sheep? (1968) is a science fiction novel by Philip K. Dick. It tells the story of bounty hunter Rick Deckard, stalking almost-human "Nexus-6" androids (referred to derogatorily as "andys") through the gloomy, partially deserted streets of a future San Francisco.

The androids are given as slaves as an incentive to colonizers of Mars, but are illegal on Earth. They can be differentiated from true humans in only two ways: the Voigt-Kampff empathy test, and a bone marrow scan (so, strictly speaking, the term android is not an accurate one.)

The future portrayed is a bleak one, in which many people have emigrated off-world. Animals are extremely rare, and hence extremely valuable. In fact, owning an animal is something of a status symbol. For many, an artificial animal is the only affordable alternative. Rick Deckard himself owns an electric sheep.