The film begins in 1965, when disc jockey Adrian Cronauer (Robin Williams) is assigned to take over the AFR's Saigon radio broadcasts. In contrast to the dull, by-rote announcers that have preceded him, Cronauer is a bundle of dynamite, heralding each broadcast with a loud "Goooooood morning, Vietnaaaaam," playing whatever records tickle his fancy (even those not officially sanctioned by his hidebound superiors), and indulging in wild flights of improvisational fancy. Cronauer's immediate superior Lt. Hauk (Bruno Kirby), whose own notions of humor are puerile and pathetic, jealously attempts to dethrone Vietnam's favorite rock jock. Fortunately, Cronauer's popularity is such that he enjoys the full protection of the higher-ups. But when Cronauer, after experiencing the horrors of war first-hand, insists upon telling his listeners the truth instead of the official government line, he is instantly replaced by the unfunny Hauk and must struggle to get back on the air.