The year is 1955, and for unknown reasons, doppelgangers have suddenly surfaced as a major issue. Thankfully, the Doppelganger Detection Department (D.D.D.) has taken action on the matter. They have hired you as their new doorman for an unknown apartment, where your job is to verify all residents that request entry into the building. However, it's not as easy as it sounds, for a single slip-up could single-handedly bring your job to a premature end.