Franco Cocussa and Ciccio Fisichella are two Sicilian card-shark con artists who arrive in Naples to plan their latest short cons, but discover they are no match of the wily Neapolitan locals, who soon figure out how their trick is done and pass the news around. Soon the two dim-witted crooks are broke and despairing. After a complicated interaction with the local police involving the death of Pasqualino, a member of the local clan of the Camorra (Neapolitan Mafia), the two decide to leave Naples, and following the advice a vagrant they meet on a cattle train, the head for the place to really lay low: Franco and Ciccio enlist in the Italian Foreign Legion and are sent to North Africa.
After their arrival, naturally everything begins to go wrong. While the bullying Sergeant Trafford sees Franco and Ciccio for the morons they really are, the Commandant of the Legion believes them to be dangerous criminals. Impressed by their inability to comprehend everything around them, the Commandant employs Franco and Ciccio as spies and ends them to infiltrate the courts of a local Arab sheikh named Mustafa Adul Bey.
The two numb-skulls are soon hiking across the vast desert where they soon suffer from heat exhaustion and start hallucinating. When they see a soft-drink vendor with an iced truck to Coca Colas, they decide not to be suckered by such a obvious mirage (the vendor is real). When Franco and Ciccio walk away, the vendor says to himself: "I've been wandering around this desert for six months, but everyone thinks I'm a mirage so I haven't made a dime!"
The dumbbell Franco and Ciccio arrive at the Sheik's oasis and find themselves embroiled in a power-play between the randy Sheik, who thinks of nothing but sexual novelty, while at the same time his conniving cousin, Sadrim Bey, plots to assassinate him. When a vacancy for two new wives arise, Franco and Ciccio don silks and veils to spy on the royal court. Unfortunately, the Sheik finds them irresistible....