By CHRISTOPHER KELLY On an ordinary morning in New York City, a quartet of mysterious-looking men in sunglasses step onto the downtown-bound No. 6 subway train. The motorman is immediately relieved of his duties. The first person to notice something might be out of the ordinary is Walter Garber (Denzel Washington), the dispatcher at the New York City Transit Authority central office.He can’t make contact with the motorman after the train suddenly stops in the middle of the tunnel.