In a dystopian near-future Los Angeles, a couple, Katie (Callies) and Will (Holloway) Bowman live with two of their three children under a regime of military occupation by an organization known as the Colony Transitional Authority. They are part of a larger invading force of extraterrestrial origin who are referred to as the “Hosts”, and as the “Raps”, apparently a reference to raptors (the logo of the human collaborating forces features a stylized bird of prey). It is said of them that “no one ever sees them”. The Hosts have built an enormous wall, around 20–30 stories tall, several meters thick, and many miles in length, which surrounds the central part of Los Angeles, where the series is set. Other similar walls have been constructed around other major cities (now called “Blocs”), while various buildings still display severe damage from the armed conflict during the invasion, known as the “Arrival”.