Hoping to destroy the corrupt power structure of a southern state, Federal agent Ray Faulkner poses as a road gang convict, engineers the escape of a group of hardened chain-gang criminals, and persuades them to work on the side of the law by promising them paroles. After training the men in high-speed driving and hurling lighted bombs at pinpoint targets, Faulkner prepares to move against a statewide moonshine syndicate. One of Faulkner's convicts, Frank Davis (a former driver for the syndicate), is at first hostile to the idea, but he becomes an eager convert when Faulkner reveals that the mob murdered his brother. Also assisting Faulkner is young Stewart Martin, a Federal agent on his first assignment. Once ready, the team of eight starts intercepting the moonshiners' delivery cars until the syndicate leader, Burl, is forced to give Faulkner and his men a share of the illegal whiskey operation and let them make the deliveries. But Burl pulls a double-cross by arranging for Faulkner and Martin to be ambushed by crooked police while making a moonshine run, and Martin is shot down from a police helicopter. By now, however, Sonny, one of Faulkner's men, has learned the location of Burl's stills and "the devil's eight" attack with their specially equipped cars and carefully timed explosives. During the battle, Burl tries to escape by using his mistress Cissy (who was once Davis's girl friend) as a hostage, but Faulkner succeeds in apprehending him. Cissy is reunited with a reformed Davis, and as Burl is being led away to face trial, Faulkner becomes confident that the power structure will soon crumble.