American thriller starring Timothy Bottoms as a young man who terrorises the American public by placing bombs at a variety of amusement parks. His next target is the country's most popular rollercoaster, and it is left to safety inspector Harry Calder (George Segal) to calm the spreading panic. When they receive a ransom demand, Harry is chosen to deliver the money and while the FBI attempt to pinpoint the bomber's position, Harry does his best to reach the explosive device before it detonates.