A Welsh mining family faces the struggles of life together.

As fifty-year-old Huw Morgan prepares to leave his home in Cwm Rhondda, Wales, he reminisces about his family and life in his beloved valley. His memories turn to his father Gwilym, mother Beth, sister Angharad and his five older brothers, Ianto, Ivor, Gwilym, Davy and Owen. One afternoon, young Huw's world changes forever when he falls in love at first sight with Bronwyn, the beautiful young woman who is engaged to Ivor. The new preacher, Mr. Gruffydd, conducts the wedding ceremony, and he, too, finds love when he and Angharad catch each other's eye. Soon after, trouble begins when C. Evans, the owner of the coal mine, notifies everyone that wages are to be reduced. Morgan tries to rectify the situation, but when he cannot, the younger miners, including Davy and the other boys, want to organize a union and strike. Morgan refuses to allow the boys to discuss the issue at home, and so Davy, Owen, Ianto and Gwilym move out. The miners strike soon after, and as twenty-two weeks pass, everyone in the valley grows hungry and desperate. Some of the miners blame Morgan for their problems because of his opposition to the strike and begin to harass him. One bitter winter night, Beth has Huw take her to a miners' meeting, at which she castigates those who have mistreated her husband. On their journey home, Beth falls into a freezing river, and Huw dives in and valiantly holds her head above the water. The returning men find them, and sometime later, Huw overhears the doctor tell his family that Huw may never walk again. Gruffydd refuses to let Huw despair, however, and his gentle encouragment keeps the boy's spirits up. On the first day that Beth is well enough to leave her bed, Ianto, Davy, Gwilym and Owen move back home and are pleased when Gruffydd approves of the union, although he urges them to take their responsibilities seriously. Gruffydd and Morgan settle the strike with Evans, but the family suffers nonetheless when Owen and Gwilym leave for America. On a spring day soon after, Gruffydd fulfills his promise to take Huw up on the mountain to pick daffodils for Beth, and there, Huw takes his first steps since the accident. Gruffydd's relationship with Angharad does not progress as well, however, because he refuses to subject her to the hard life of a preacher's wife. Deeply hurt, Angharad weds Iestyn, Evans' son, and moves with him to South Africa even though she still loves Gruffydd. Meanwhile, Huw passes the exams for the national school and begins attending classes in the next valley, where he must deal with local bully Mervyn, and the English Mr. Jonas, a cruel teacher who hates the Welsh. One night, soon after Ivor is killed in a mining accident, Bronwyn gives birth to their son, and Huw, who has decided to work in the mine rather than attend university, goes to live in her house to keep her company. Conditions in the mine worsen and Ianto and Davy are dismissed so that Evans can hire new workers for less pay. Ianto then leaves for Canada and Davy goes to New Zealand, while Angharad returns from Capetown without her husband. She lives alone in the nearby Evans mansion, and soon the housekeeper, Mrs. Nicholas, begins spreading gossip about Angharad and Gruffydd, even though they have remained apart. The talk angers the Morgans, who refuse to attend chapel anymore after the hypocritical deacons speak out against Angharad. Gruffydd resigns from his post as well, but as he and Huw are saying farewell, they hear the warning whistle from the mine. They rush to the site and learn that Morgan and others are trapped below. While the men at the top pump out water, Huw and Gruffydd lead a rescue party into the shaft. Huw finds his father, who hugs him before dying, then takes his body above to where Beth and Angharad are waiting.