Fast-paced action adventure following a Los Angeles SWAT-team cop's attempts to foil the plans of a deranged bomber. The cop cheats his quarry out of one ransom, but, in response, the psycho contacts him with a warning about a bomb on a bus which will explode if the speed drops below 50mph. With the help of a female passenger, the cop attempts to navigate the bus around the crowded streets of LA while keeping its speed constant.