In 2019, the world has totally been transformed.
The needs of the population have reached some very dangerous levels. So the cities have evolved to polluted megalopolis.
The animal life had been almost erased from the surface of the planet. The "replicants" are in charge of the dangerous and uncivilised tasks.
These androids have the same biological functions than the human beings except their life expectancies. In exchange they have some special skills adapted to their tasks.
When there is a dysfunction with these "replicants" they have to be "retired". This a job for the "Blade Runners".
"All those moments will be lost in time like tears in rain."