In a post-apocalyptic world, humanity lives in small settlements whose main activity is to produce electricity.

Jack Traven, an LAPD cop on SWAT detail, and veteran SWAT officer Harry Temple thwart an extortionist-bomber's scheme for a $3 million ransom. As they corner the bomber, he flees and detonates a bomb vest, seemingly killing himself. Weeks later, Jack witnesses a mass transit city bus explode and nearby a pay phone rings. On the phone is that same bomber looking for vengeance and the money he's owed. He gives a personal challenge to Jack: a bomb is rigged on another city bus - if it slows down below 50 mph, it will explode - bad enough any day, but a nightmare in LA traffic. And that's just the beginning...