White Lightning (1973)

Good ol' southern boy Gator McKlusky has served four years of his five year prison sentence for moonshining, he up to this point a model prisoner. When he learns that his younger brother, college student and activist Donny McKlusky, was murdered, his bound dead body found in a Bogan County Lake, he is able to convince the authorities to release him early in return for him finding evidence against the suspected culprit, Bogan County Sheriff J.C. Connors, not for the murder of which they have no idea of the McKluskys' suspicions against Connors, but concerning an active but somewhat cold IRS file, namely yet unproven but well known unreported lucrative profits in bilking moonshiners. They also know that the sheriff is crooked in other ways, but the IRS only has the jurisdiction on the tax evasion issue. They provide Gator with a souped up car fit for moonshine runs that would be able to outrun almost any on road vehicle, and a contact in Bogan County, Dude Watson, a mechanic who has no option but to cooperate, despite his own fears about Connors, in he being a con on probation, the conditions which they know he has broken. Dude in turn is able to set Gator up with moonshiner Roy Boone to infiltrate the business in the county as one of his runners. The IRS's goal, which has its inherent risks for Gator in he needing to provide names of moonshiners, is secondary for Gator who solely wants to avenge Donny's murder. But Gator may have bigger problems if the Sheriff gets wind that the feds are after him via Gator and/or Dude, they or anyone connected to them possibly ending up the way of Donny if he has his way.