Francis Mosses is the diligent doorman at Apartment 61, working for the Doppelganger Detection Department (D.D.D.). He is responsible for protecting residents and identifying potential threats. While he is familiar with most residents' routines, the milkman's erratic schedule and suspicious behavior have raised significant security concerns. Francis is determined to investigate whether these anomalies indicate a doppelganger or other mysterious activities within the building.