Rosco chases Bo and Luke, and the sheriff tries to outwit his adversaries by fooling them into driving over the county line – and thus making it grounds for probation revocation.
Just another normal day in Hazzard County – not!
While unknowingly having crossed the county line, the Dukes happen across a dirt track, where NASCAR racer Cale Yarborough and his assistant, Chet Garvey, are secretly testing a turbocharger.
The Dukes introduce themselves and learn that Cale's rivals – the wily Jethro brothers, Simon and Rowby – have learned that the racer is possibly testing an engine device and aim to obtain it by whatever means necessary. Bo and Luke offer to help Cale and Chet sneak the turbocharger out of the area to the site of the Illinois 500, where Cale plans to unveil the new engine for the first time.
Meanwhile, the Jethro brothers approach Boss to help them get ahold of the turbocharger, offering $25,000. Of course, Boss accepts. The Jethro brothers then place "bugs" inside both the General Lee and Cale's car to monitor the Dukes' and Cale's every move.
The Dukes, Cale and Chet decide that they will split up, so they can easily get the turbocharger transported to Illinois without Cale being seen with it.
Bo and Luke try to get Cale to the bus station, then the train station and later an airfield. But Rosco and Enos seem to be everywhere they show up, leaving the Dukes befuddled and the local law full of adreneline as they play cat and mouse once again.
Bo and Luke finally manage to lose Rosco and Enos (making the jump that we see in the opening credits in later seasons), and then find the "bugs" inside each of the cars. Once the Dukes disable both listening devices, they enact a final plot to fool Boss, the Jethro brothers and the local sheriff's department.
That's done by painting a pair of faux General Lees, and then having Jesse drive one and Daisy the other, while Bo and Luke try to get Cale to his destination in the real General Lee. After totally confusing Boss, Rosco and Enos, Cale finally makes it to the Illinois 500.
BTW – Cale wins the race, while the Jethro brothers, who came up empty-handed in getting the turbocharger, finish in last place (which Waylon notes "is a lot better than they deserved").