Rosco (Terence Hill) is an engagingly carefree traveller with a gift for ventriloquy, roaming the highways by any means available, and he is nearly injured by a large truck driven by two heavies. Doug (Bud Spencer), a bearded giant, is newly-released from the state penitentiary, and is enjoying his lunch in a truck stop when Rosco discovers the homicidal truck parked outside and bursts in to find the drivers. With Doug's help, Rosco gets his revenge. When they leave the remains of the truck stop, they discover neither has any plans nor anywhere to go and they end up taking a truck-each man con-vinced that it belongs to the other. Stopped by police, they escape in a squad car. At the nearest airport, Rosco convinces a booking clerk that they are two late passengers, Steinberg and Mason, who are being called over the public address system, unaware the real Stein-berg and Mason are special agents travelling on a special mission. Before take-off, a man hands Doug and Rosco an attached case and leaves the plane. Inside the case are documents and a million dollars in cash. The plane lands in Miami where Doug and Rosco are met by a small army of CIA agents who have tracked them through a transmitter hidden in the case. They are welcomed by the head of the CIA who is proud to meet the two most secret agents serving the nation, so secret that only one man knows their real identities and he's the CIA's top chief. Doug and Rosco are equipped with every gad-get in the CIA armony and they find that they have no hope of extri-cating themselves from the dangerous mission assigned to them. Their adventures take them through a fun fair, a night-club, a glue factory and a variety of locales until, eventually, they track down the evil mind plotting to steal the Space Shuttle. Thanks to Doug and Rosco, the Shuttle, the city, the state, the USA and the world are all saved-in the nick of time.