In the dystopian year of 2000, the United States has been destroyed by a financial crisis and a military coup. Political parties have collapsed into a single Bipartisan Party, which also fulfills the religious functions of a unified church and state. The resulting fascist police state, the United Provinces, is headed by the cult figure "Mr. President" (Sandy McCallum). The people are kept satisfied through a stream of gory gladiatorial entertainment, which includes the bloody spectacle of the Annual Transcontinental Road Race, depicted as a symbol of American values and way of life. The coast-to-coast, three-day race is run on public roads, and points are scored not just for speed, but for the number of innocent pedestrians struck and killed.
Frankenstein (David Carradine) is the most celebrated racer and is the government's champion. He is reputed to be part machine, rebuilt after many crashes. He regularly battles with the other teams, particularly "Machine Gun" Joe Viterbo (Sylvester Stallone), who hates being second.
The film is set at the start of the 20th annual race, during which a resistance group led by Thomasina Paine (Harriet Medin), a lineal descendant of Thomas Paine, one of the original American revolutionaries of the 1770s, is attempting to assassinate Frankenstein and replace him with one of their agents. The "Resistance" is assisted by Paine's great granddaughter Annie (Simone Griffeth), Frankenstein's navigator, who is intending to lure him into a planned ambush where he is to be replaced by a double. Disruption of the race by the Resistance is blamed on the French by the state, who are also blamed for ruining the country's economy and telephone system.
It emerges that Frankenstein is not a willing government stooge, nor is there a single Frankenstein. The current Frankenstein is simply one of many people specially trained to race in the role. "When one is used up, they bring in another," he tells Annie. The current Frankenstein also has his own plan to end the tyranny: win the race and shake hands with Mr. President, detonating a grenade which has been implanted in his prosthetic right hand (he refers to it as a "hand grenade".)
Frankenstein successfully outmaneuvers both the rival drivers and the Resistance, and is declared the winner and sole survivor, although he is wounded and unable to carry out his original grenade attack plan (with Annie using the grenade to kill Joe Viterbo when he attacks them near the end of the race). Annie dons Frankenstein's disguise and plans to stab the President on the victory podium. Greeting the president as he congratulates Frankenstein (and declares war on the French), Annie is mistakenly shot and wounded by her grandmother. Frankenstein finally succeeds in killing the President by ramming the podium with his car.
In an epilogue, Annie and Frankenstein are wed, and Frankenstein, now President, abolishes the race and the perverse laws of the Provinces, though he does make a point of running over objecting (and objectionable) reporter Junior Bruce (Don Steele) whom appears throughout the movie covering the race.