La Gran Fiesta is set in 1942, when relations between the Continental United States and Puerto Rico were delicate at best. Casino de Puerto Rico, a lavish San Juan nightspot, is about to be turned over to a recreational center for US troops. To celebrate their last night as a "civilian" nighterie, the staff members of the Casino stage one final all-stops-out Grand Ball. Everyone is invited, even those "undesirables" who would normally be shut out of the black-tie establishment. The names of the film's stars will probably be unfamiliar to a non-Latino audience; most filmgoers, however, will quickly recognize Raul Julia and E.G. Marshall in their brief guest appearances. Though many American films and TV programs had previously been lensed in Puerto Rico, La Gran Fiesta was the first feature-length film to be produced by the Puerto Rican film industry itself.