Iron Road follows the journey of Little Tiger (Sun Li), a child whose quest for her long-lost father takes her from a fireworks factory in China to a remote construction camp in the Rockies. Lured by the myth of 'Gum San' - Gold Mountain - she and her countrymen come to Canada by the thousands to do the back-breaking work of blasting through the mountains to lay track. She soon learns that rail roads only bring fortune to the few and that every mile of track is purchased with fear and death. As treachery and prejudice threaten her, Little Tiger must use her wits and courage to fulfil her quest and honour her friends who died in this foreign land.

Little Tiger disguises herself as a man, but develops a crush on the contractor's son, James Nichol. They become friends, him treating her as just "one of the guys." At one point, he takes his clothes off and jumps into a river for a swim, asking her to join him. She declines profusely, but secretly glances at his naked form when he isn't looking. Later, she reveals to him that she is a woman and confesses her attaction. They begin an affair, which continues until disrupted when the Chinese construction foreman dies saving her when her safety rope breakes as she places dynamite charges on a cliff. It is discovered that the foreman is actually the father she has been looking for and that the rope had been sabotaged deliberately. Learning that her father's last wish was to have his ashes returned to China, she decides to leave the railway camp to do so. James wants to leave Canada with her so they can spend their lives together, but she refuses because they are from different worlds and she fears the "social implications". Interracial or inter ethnic relationships was generally discouraged at the time.