Garber (Denzel Washington) did take a $35,000 bribe when he saw the improved train models in Japan. Ryder (John Travolta) was a Wall Street broker who went to prison for 10 years for embezzlement. He hijacked train 123 on route 6 not as a terrorist act, but to tip the stock market such that the value of gold would skyrocket from $2 million to just over $300 million.
Ryder and two of his henchmen make off with their equal shares of the $10 million hostage fee. The two goons are caught and shot by police at and intersection while Garber follows Ryder who has escaped in a cab. Garber eventually finds Ryder on the Manhattan bridge, and shoots him once in the chest.
As thanks for his service, the mayor (James Gandolfini) promises to erase the investigation into Garber's bribe. Garber returns home to his family with a half gallon of milk.