The Domain of the King is a 1950's diner with a Pink 1959 Cadillac Coupe de Ville convertible usually parked out front. Both are owned by Elvis Aron Presley, who found himself in the multiverse after faking his death. The diner flicks between dimensions, following a pattern which nobody has ever been able to discern.
The diner is an incarnation of the Inn of Dionysos, also known as the Inn of Bacchus. At various times different people have worked there, including a cute young dæmon named Lillith, and a hitch-hiker named Arthur Dent.