In 1933, the height of the Great Depression, the fields in Shulls Mills, Virginia have dried up during one of the longest droughts in U.S. history. Bill Music, a courageous farm boy and his hard-working parents stand to lose their family farm to foreclosure. But Bill is hopeful in his belief he can save his parent’s farm and travels to Chicago to find work. He studies hard and becomes a certified electrician.

But Bill’s hard-earned life turns dark the day his foreman throws a switch that will electrocute and severely injure him, making him unemployable. He struggles to survive, but the day he is robbed of his last $20 he throws in the towel and hobos his way home in a boxcar, cynical and defeated. When the train reaches Kentucky, he leaps off to find food and sleeps for the night in a hay bale on a farm owned by Regus Bone, a mine guard for Hardcastle Coal Company, and his religious mother, Ella Bone.

Regus suspects Bill of being a union man but Bill convinces him he is just a man trying to get home again. The next morning Ella tells of a dream she had that God commanded her to take Bill in. Regus offers Bill a place to stay and offers him a job as his partner and mine guard at the coal mine for the princely sum of $3 a day. Bill’s faith is restored in humanity and he accepts the work, excited to send money home again. Quickly, Bill begins to question his decision when he learns he must carry a gun and evict poor miners and their families, no questions asked. But the paycheck is hard to refuse and Bill remains.

Bill’s boss, Kenton Hardcastle, is a man used to his luxuries and dedicated to making a buck. But Hardcastle struggles financially and the union keeps sneaking in to rile up his miners. He cuts corners on mine safety to save money and pays off the inspector to stay out of the dangerous mine. He employs his niece and nephew, Gradine and Cawood Burnside, two deadly individuals willing to do whatever their uncle asks of them. But Gradine's loyalty slowly erodes when Hardcastle is dismissive with her and demands she find a husband so he doesn’t have to support her forever. She has no wish to marry, let alone be with a woman. Her love for her brother also wavers after she discovers he’s a sexual predator that preys on the young Black girls in the coal camp.

Bill joins Regus to deliver yearly “yellow dog” contracts for the miners to sign that promise no union involvement. While delivering those contracts, Bill meets Merlee Taylor, a bitter widow whose husband was “accidentally” shot by Gradine for stealing a little ribbon from the company store. Although Kenton Hardcastle has graciously allowed Merlee to remain in company housing, she and her baby have no financial support except meager supplies from the Federal government.

Bill is immediately drawn to Merlee but she won’t have a thing to do with a mine guard so he approaches the prickly Merlee cautiously and gifts her with staple goods and some pretty material to make a new dress. She slams the door in his face often but eventually softens and invites Bill into her home and they become lovers. But Cawood has his eye on Merlee too. He peeps on her only to find himself at the wrong end of her shotgun. Gradine catches Cawood skulking away and she posts herself outside Merlee’s to guard her for the night.

In the meantime, a Black preacher/miner, Lewis Porter, meets with union leader Tony Zigerelli, for a secret meeting with other miners. While out on his nightly patrol, Bill catches them sneaking into a meeting but does nothing. The next day there is an explosion that kills eight miners. During the chaos, Bill and Regus discover the boxes holding gas masks that would allow others to get in and rescue the trapped men are empty; a deadly cost-cutting measure by Hardcastle. During this, Cawood and Gradine show up to help, but Cawood heads straight for Bill to scrap with him over Merlee. Bill ends up shot in the butt and Cawood is knocked out. Bill’s conscience gets the upper hand and he decides to quit. But before he leaves he promises to help Regus arrest the union men.

Hardcastle, who needs housing for the replacement of the dead miners, orders the eviction of the eight widows. This does not set well with Gradine, who stands by silent in her anger. Hardcastle demands Regus deliver the eviction notices. Ella shames Regus for following through with this order and Regus is torn. Ella takes matters into her own hands and meets with the widows to write a letter to the governor about their eviction and to tell him about the safety crimes at the mine.

When he and Bill arrest the union men, he surprises Bill by letting them loose and decides to quit too. Hardcastle finds out about the secret union meetings and evicts Lewis and the miners involved. Regus allows the evicted families to set up camp on his property. He and Bill march into Hardcastle’s office and quit. Hardcastle does not take this lightly and swears they will never find work again.

Bill and Regus travel to Tennessee for food and supplies in Tennessee for the evicted families and face roadblocks with armed men going and coming back. When they return that night Merlee visits to show off the new dress she made from the material Bill gave her. Bullets wick the side of the cabin and Hardcastle thugs dynamite the evicted families on Regus’ property, killing Lewis’ son. Lewis, Regus and Bill turn to the Sheriff to arrest the murders but the Sheriff blames them for the problems and offers no assistance.

Enraged, the miners want to raid the company store, but Regus calms them with plans to remain on strike, even though they’re pretty much beat. This will make Hardcastle pay money he doesn’t have for more hours of security and scabs. Regus turns for home when he’s shot dead. Bill opens fire on the shooters and hits Cawood. Cawood rises to kill Bill, who is out of bullets. Another shot rings out that kills Cawood. Gradine steps out of the shadows, her gun at her side. The next morning, Hardcastle and the Sheriff arrest Bill for killing Cawood and drag him to a mountaintop for some small-town justice. Gradine is with them, but remains silent about Bill’s innocence.

The Sheriff has nearly beat Bill to death when Gradine allows Bill to escape over an embankment. At the bottom of the hill Bill finds an amazing sight; every person in town has rallied to save him. Hardcastle and the Sheriff, who have followed Bill, are told the Governor is arriving in a few days to investigate mine impropriety. Hardcastle can either come up with a good story or leave town. Gradine is nowhere in sight. As Hardcastle lets the ultimatum sink in, an explosion below blows his mansion to pieces. Gradine has her justice. Bill and Merlee marry. Bill learns that President Roosevelt’s Emergency Farm Act rescued his family’s farm from foreclosure. The Governor of Kentucky signed over the ownership of Hardcastle’s mine to a new coal master, Lewis Porter, who changes the name to Freedom Mine.