In a settlement in the northern mining country. The Marles, Bréhard and Gohelle families wake up and prepare for a new day at work. The young engineer Larzac, newly appointed to the mine, will soon oppose the authoritarian and conservative methods of his superior Dubard. Georges Gohelle would like to marry Marie Bréhard, but housing difficulties thwart their plans. Brezza, a Polish immigrant, who must return to his country, would like to hate his marriage to Louise Gohelle. Roger, Marie's little brother, has just turned 14. He does not want to go down to the mine as his elders have always done. He will however have to resign himself to it. Marles evokes for him the social struggles of 1906. Roger is injured during a landslide. In front of his family and his friend Marles, who had come to the hospital, he announced his decision to continue his profession. Larzac, invited to the Marles, reveals that he refused a quiet position at the Charbonnages de Paris. He too stays.