The biggest question unanswered in the original "Blade Runner" film, set in Los Angeles, in the year 2019, is whether or not 'Rick Deckard', the "one-man slaughterhouse", forced into killing android 'replicants', is also unknowingly, a replicant himself.
Scott's "Blade Runner" film was based on author Philip K Dick's novel "Do Androids Dream of Electric Sheep".