An opening statement asserts: 'Every year 12,000 miners die in work-related accidents.'
In Copiapó, Chile, many men strive to extract gold from the perilous depths of the San José mine. Mario (Antonio Banderas) takes on additional shifts to provide for his beloved wife Katty and their daughter Escarlette. On the other hand, Álex (Mario Casas) ponders taking a safer job that promises lower pay, hoping to ease the worries of his pregnant wife Jessica and father Don José. Darío (Juan Pablo Raba) prefers to sleep on park benches rather than accept help from his estranged sister María (Juliette Binoche). Meanwhile, Yonni (Oscar Nunez) entertains his fellow miners with tales of his romantic exploits, while Edison (Jacob Vargas) adds flair by dressing like an Elvis impersonator. In the chaos, José ([Marco Trevino]) serves as a pastor to his fellow miners, while shift foreman Luis (Lou Diamond Phillips) grows increasingly concerned about the mine’s safety. As the oldest member of the crew, Gomex ([Gustavo Angarita]) looks forward to retirement in just two weeks.
On August 5, 2010, Day 1 begins. Mario, Álex, Darío, Yonni, Edison, José, Gomex, Luis, and others board a shuttle bus destined for the mine. Passing through the desert, they see Carlos ([Tenoch Huerta]), a Bolivian newcomer, but their shuttle does not stop for him. Before their shift starts, Luis visibly anxious storms into his boss Castillo’s office. While examining the mine's underground stability, he discovers a shard of glass—a sign that mirrors placed among the mountain’s fissures have shattered, indicating a dangerous shift. Luis urges for the mine to be closed, but Castillo disregards his warnings. Shortly after, Edison lashes out at Carlos for his Bolivian roots, hinting at lingering prejudices. As they enter the narrow tunnel of the mine, Carlos struggles with claustrophobia.
The Machine Shop at the dig site, located 1,700 feet under ground and a sweltering 90°F, becomes the battleground where they work. Luis continues to inspect the tunnels and notices more broken glass. Mario shows Carlos the ropes of operating an excavator while Álex contemplates his decision about the job. Suddenly, the earth trembles violently; boulders cascade down, sending everyone fleeing towards the Refuge—a safety station 2,300 feet underground and 94°F. The trucks struggle in the chaos, and above, the mine’s entrance collapses in a cloud of dust. A total of thirty-three workers find themselves trapped.
Up on the surface, Castillo orders the mine to be shut down, attempting to prevent anyone from leaving. Some miners manage to escape in their vehicles before the gates are barred, contacting the media to announce the disaster. Heartbroken families rush to the mine’s gates, demanding information about their loved ones. Laurence Golborne (Rodrigo Santoro), the minister of mining, briefs President Pinera (Bob Gunton) that the mining company cannot execute the rescue alone. New to his role, Laurence effectively persuades the president to intervene.
Underground, the miners gather to discern their grim situation. A massive boulder blocks their way out. Luis suggests heading to the Refuge, where they could survive for three days with available provisions. However, Mario refuses to surrender. He believes inspecting the mine's ladders could reveal a pathway to freedom. Álex joins him, ignoring Luis's objections.
Day 2 unfolds. Mario and Álex brave the ladders, but their hope shatters when they discover they only reach halfway up the chimney. To their dismay, Luis reveals that communications devices in the Refuge were never completed. Tensions escalate when Darío attacks Yonni to access food rations. Amidst dwindling supplies, a riot erupts over the scant provisions. Mario steps up, earning respect and leadership among the miners as he controls ration distribution.
Above ground, Laurence arrives at the mine site, where he is confronted by María, who demands reassurance that the miners will be saved. Castillo reveals his failed attempt to send rescuers underground. Laurence delivers this bitter news to the miner's families, where María harshly criticizes him for letting them down. The president calls upon André Sougarret, a reputable mining engineer, who warns Laurence that reaching the trapped miners could take weeks, compounded by the unpredictability of the rock bed.
Day 3 arrives. Below ground, Mario manages rations while maintaining morale as the Refuge's lights are restored.
Day 5—the drilling continues, though it suffers frequent breaks due to the mountain's hardness. Frustrated, André chastises Laurence's incessant questioning as families impatiently await updates. Meanwhile, the miners grapple with withdrawal and discomfort but find solace in shared camaraderie.
In a coming-of-age realization, as Day 8 approaches, makeshift Camp Hope flourishes, where Katty and Escarlette prepare food while Jessica educates the miners' children.
Day 14 marks a glimmer of hope as a drill finally reaches the Refuge, exhilaration fills the air. However, this excitement turns to despair when they realize the drill has bypassed their location. Álex, overwhelmed, attempts to self-harm. Mario discourages these thoughts, reminding him of his parental duties. Hope wanes as the men consume their last rations, but André and Laurence devise a new strategy based on previous miscalculations, redirecting the drills to the fissures in the rock.
On Day 17, Mario witnesses the miners’ deteriorating mental states. A breakthrough occurs when one drill punctures the cavern above them, leading to an outpouring of joy as they bang against the drilling machine. Laurence hears the noise, and relief floods through them when the miners communicate their survival to President Pinera and their families.
Weeks drag on as the rescue team establishes communication with the men. They shower the miners with provisions—iPods, magazines, new clothes—sparking significant morale improvements while physical conditions begin to decline due to the cramped quarters. Mario's role as the face of the miners intensifies competition and envy amongst them, culminating in Edison leading a coup to reclaim leadership.
By Day 58, tension rises when Luis realizes the drill's trajectory poses a risk of hitting a support beam. The miners propose using a controlled explosion to remove the beam, consenting to the dangers involved. Meanwhile, the families anticipate the men’s imminent rescue, even as personal struggles surface among loved ones.
On October 13, 2010, the extraction capsule finally arrives at the Refuge. Álex is chosen as the first to ascend, promising his comrades he will reunite with them above ground. The process unfolds smoothly, and as each miner emerges, they are greeted with cheers from their families and supporters. “We did it!” Mario exclaims, igniting a frenzy among the crowd. As the last to be rescued, Luis steps into the capsule, concluding an arduous journey.
In the aftermath, the San José Mining Company was acquitted of criminal negligence, leaving the miners uncompensated. Despite this injustice, the bond they formed throughout this perilous ordeal endures, and their camaraderie persists to this day.
