Chillingly visual chase scenes take place along the tracks of N.Y.'s Triboro subway system at night in a tale of extortion/revenge. The hero is Harry McKenna of the subway police force. His job is to capture the limping man who had demanded a fortune of the subway's union to stop killing their motormen. Harry's role is complicated by the fact that his girl has been kidnapped by the extortionist. Organized to the split second, this hurtles along with the force of a subway train.