Filmed as Blade Runner, Do Androids Dream of Electric Sheep? (1968) is 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 incentive to colonizers of Mars; they are illegal on Earth. They can only be differentiated from true humans in 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.