Raoul Duke and his attorney Dr. Gonzo drive a red convertible across the Mojave desert to Las Vegas with a suitcase full of drugs to cover a motorcycle race. As their consumption of drugs increases at an alarming rate, the stoned duo trash their hotel room and fear legal repercussions. Duke begins to drive back to L.A., but after an odd run-in with a cop, he returns to Sin City and continues his wild drug binge.

Low-level bureaucrat Sam Lowry escapes the monotony of his day-to-day life through a recurring daydream of himself as a virtuous hero saving a beautiful damsel. Investigating a case that led to the wrongful arrest and eventual death of an innocent man instead of wanted terrorist Harry Tuttle, he meets the woman from his daydream, and in trying to help her gets caught in a web of mistaken identities, mindless bureaucracy and lies.