The story of Vigilante 8: 2nd Offense centers on the international meddlings of an oil conglomerate from the future known as OMAR (Oil Monopoly Alliance Regime). After finding an electronic armband in a service station bathroom, former Vigilante Slick Clyde rose to be controlled by OMAR. Working up through the ranks of command he soon came to be the CEO of OMAR itself and made a complete monopoly on all oil trades with the sole exception of the United States. With the help of his student and hitman, Obake, he steals the technology to allow him to travel through time. Taking with him Obake and his cybernetic assassin, Dallas 13, he makes the jump back to the 1970s to cripple the United States and bring OMAR to total domination. Appearing in the 1970s, the three vehicles encounter Convoy, the former leader of the Vigilantes. Upon seeing him, the three cars open fire.
The game is set in September 1977, two years after the events of Vigilante 8. The southwestern United States has become peaceful in the wake of the Coyotes' defeat, but the Oil Monopoly Alliance Regime (OMAR) continues to dominate most of the global petroleum market, well into the 21st century. With new Coyotes leader Slick Clyde leading OMAR during the twilight of his life by 2017, Clyde thinks that a failure to conquer America (which has adopted nuclear and sustainable energy) would be his biggest regret. He plans to change history by stealing prototype time machines from Stanford University's quantum physics lab, travel back to the 1970s, and eliminate the Vigilantes to ensure OMAR's supremacy.