When a roller coaster in California goes off its track, killing several people, safety inspector Harry Calder, who had recently inspected the coaster, is assigned to investigate. After another amusement park suffers a suspicious fire, Calder uncovers a blackmail plot by a psychopathic terrorist. The terrorist seems to know everything Calder and the FBI say and do, and insists that Calder deliver the blackmail money personally at an amusement park in Virginia. After running Calder all over the park, the money drop is made and the terrorist gets away, but he discovers that the FBI had marked the money, making it useless to him. He plots to get revenge by blowing up a giant new roller coaster on its opening day, and it's up to Calder to stop him.