In Mississippi at the turn of the 20th century, 11-year-old Lucius McCaslin (Mitch Vogel) embarks on a journey he will remember for years to come. When Lucius' grandfather, Boss (Will Geer), buys an automobile, local handyman Boon (Steve McQueen) chomps at the bit to get behind the wheel. He gets the chance when Boss takes the train on an out-of-town trip. Approaching the impressionable Lucius, Boon is able to talk the youngster into a road trip with him and his friend Ned (Rupert Crosse).