 A man tries to extort money by threatening to kill some people with explosives. And the city was about to give in when rookie cop, Jack Traven stops him. Jack and his partner, Harry find him and corner him but instead of giving up he blows himself up. He is believed to be dead but he actually escapes. He tries again this time he has placed bomb on a bus that will exploded if the bus goes below 50 mph. He dares Jack to stop him. Jack tries to stop the bus before the bomb is armed but Jack is too late; all he can do now is to keep it going. While Harry tries to find the guy.