David Goliath, Paul Robeson, is an African-American sailor who deserts his ship when it arrives in Wales. He climbs onto the back of a freight train and meets Bert, Edward Rigby, a work-shy man who scoffs at David's determination to find steady employment. The train rolls into a small mining town, and the pair briefly tries to busk before they are scolded by Mrs Parry, Rachel Thomas, for making unpleasant noise outside her shop. They pause outside a building where a male choir is rehearsing, and David bursts into song, drawing the attention of the choir conductor, Dick Parry, Leslie Phillips, who is determined to recruit him and offers him lodgings at his house.
Despite his wife’s objections, their children side with the father, and Dick persuades David to give life in the mine a try. He is soon put to work as a miner alongside Dick and his eldest son, Emlyn, Simon Lack, despite the racist objections of a lone coworker. The optimism is short-lived: Dick and David accidentally mine near a pocket of gas, triggering a devastating fire that claims many lives. Emlyn wasn’t at the site that morning and rushes in to help; David carries Dick to safety, but the conductor does not survive.
A month passes, and Dick’s choir returns in memory of their lost leader, with David performing solo as tribute. The mine has shut down, and the remaining miners scrape together coal from the spoil heap, struggling to earn what the mine previously paid them and increasingly relying on social benefits. A year later, Mrs Parry is left to raise five children alone. She is visited by Mrs Owen, Dilys Davies, the mother of Emlyn’s fiancée Gwen, who bluntly notes that Gwen cannot marry Emlyn while he cannot provide for her.
Gwen herself later visits the Parry household and vows to marry Emlyn regardless of money, which spurs Emlyn to march to London and demand that the government reopen the mine. He, David, and two other miners make the journey, arriving just after Germany invades Poland. In London, the government is focused on building up the army, and their protestors are kept at bay as the plan to reopen the mine is floated but contested. The team returns to Wales with renewed resolve to reopen the mine, yet a fierce fire engulfs the mine and collapses passages, trapping the rescuers underground.
With oxygen thinning and panic rising, David estimates they have only an hour left to live. A miner finds a weak rock and another attempt to break through with a pickaxe fails. Emlyn decides to leave the group to blast a path with dynamite, but David, aware of the danger to his companions, restrains him and knocks him unconscious, triggering the blast after seizing the dynamite. The blast forces a breakthrough, but the group wakes to find David’s lifeless body nearby, a somber moment that is honored with quiet, communal prayer for his soul.
Ultimately the mine is reopened, and the town lifts their voices in unison as coal flows once more through the tunnels, a testament to resilience in the face of tragedy and prejudice alike.
