British have been mining coal for 2000 years. In 1575, a pioneering innovation in mining techniques led to the development of mines connected via a vertical shaft which led to better ventilation and water egress. Raniganj is India's coal mine. Indian mines were designed on the basic British design. They had the same flaws that led to frequent accidents inside the mines. Flooding and fires were frequent hazards inside Indian mines, which claimed the lives of hundreds of miners at a time.In 1989, miners are undergoing a shift change around midnight in Raniganj Coalfields. The mine is divided into three sections, and a blast is set off in one of the sections to open new coal veins. Upon the blast, it is noticed that the shaft is leaking water. An emergency order is sent out to evacuate, but the Behra (deaf) section is led by a deaf miner Anant Pandey (Sudhir Pandey) who doesn't hear the phone signal. Most of the 200+ miners are evacuated except for all 60+ miners in the Behra section and 6 miners who drown trying to escape the mines.Jaswant Singh Gill (Akshay Kumar) is a manager of a nearby mine who notices the emergency vehicles headed for the mine and decides to lend his services. Jaswant is married to Nirdosh (Parineeti Chopra), who is pregnant. Jaswant has the reputation of being an upright manager, who doesn't bow down to corruption of union strong arm tactics. Upon arrival he encounters stiff resistance from other members of the operation who believe that all the miners are already dead, and a rescue is futile. A British mining expert was in Dhanbad for a conference and was called in for consultations. He also insists that there is no way that the trapped miners could be alive.The head of the flooded mine, Ujjwal (Kumud Mishra), requests Jaswant's help in the rescue operation. Jaswant adds 10 pumps to the mine to pull the water out of the flooded sections. KP Natarajan (Ananth Mahadevan) is the Chairman of CIL and OP Dayal (Shishir Sharma) is the technical director. Dayal sends Sen (Dibyendu Bhattacharya) to oversee the rescue operations at the coal mine. Sen is indifferent to the tragedy unfolding in real time.Govardhan Roy (Rajesh Sharma) is the local MLA and represents the public anger towards the officials and the managers at the mine. Sen promises Govardhan that he will rescue the workers from a nearby Ningha pit mine, which also bored directly down to the affected parts of the flooded mine. But Jaswant had also surveyed the Ningha pit mine and knew that rescue was impossible that way as Ningha pit was also flooded. Sen only wanted to bring his drilling contractors so he could charge CIL for unnecessary work.DG Om Chakravarti (Arif Zakaria) is the official in charge of mine safety. Sen presents his plan to Om, which assumes that miners are stuck near their working area. Jaswant says that miners have more than 25 years of work-ex and are trained to head to the highest point of the mine and wait for rescue. He proposes to survey the land to find the highest point of the mine, drill an 8 inch hole to locate the miners and then drill a 29 inch hole to pull the miners out in a capsule. This technique has never been used in India before. Om says that Sen's idea is more practical and goes with it, but Ujjwal stands by Jaswant and asks him work parallel to Sen.Gill recruits a disgraced surveyor, Tapan Ghosh (Virendra Saxena) and a drilling engineer, Bindal (Pavan Malhotra), to scope the highest point of the mine. Tapan had conducted an overland survey of the highest point of the mine 8 years ago. But he was blamed for an accident at a different mine (due to an incorrect survey), and his wages and pensions were stopped by the Government. Jaswant promises to help Tapan to get his dues, and his wife finds him genuine and badgers Tapan into helping Jaswant.Meanwhile, the miners are stuck about 3 kilometers from the highest point. Shaligram (Varun Badola) knows the route to the highest point of the mine, but the route is obstructed by a fast flow of water. Bhola (Ravi Kishan) is not in agreement with the plan and argues that the miners should stay put in their current location. Shaligram and the other miners (Murli, Gop and Dhaneshwar, Banke, Ranjeet) convince Bhola that if they stay put, eventually they will be flooded as well due to the rising water levels.From the highest point, Jaswant excavates an 8-inch borehole, placing a flashlight as a signal to the miners. However, unbeknownst to them, the miners are stuck behind a brick wall obstructing the path to the highest point, and do not see the flashlight.Tapan tells Jaswant about 2 stoppage walls inside the mines which might be stopping the miners from reaching the highest point in the mine. Tapan proposes another bore hole a little further from the current spot to reach the miners on the other side of the wall. Sen's crew uncovers the bodies of 6 miners who drowned, causing the rescue crew to abandon the mission and shut down operations. But the miners discover the stoppage wall behind debris and realize that they are not at the highest point of the mine. They start dismantling the wall.The flashlight is withdrawn just before the miners reach the highest point. However, the dog of one of the miners (the dog was with Jaswant above the ground) hears the miners' desperate cries and barks at Gill, alerting him that the miners are still alive, and the rescue should be continued.It is revealed that OP Dayal dislikes Ujjwal and he had sent Sen to sabotage the rescue operations. After Sen's attempt fails, the efforts focus on Gill. The 8-inch borehole allows for food, water, and medicines to be sent down to the mine, along with a communications line. Through a Davy lamp, the miners discover that the shaft is being filled with carbon dioxide gas, which along with the water is creeping towards them. Gill deduces that the miners only have 48 hours before their oxygen supply runs out. Bindal says that he will need 40 hours to drill the 29-inch borehole. Gill devises a 29-inch-wide capsule which can be used to pull the miners up one at a time from a larger borehole.Bindal's crane can only go down to 110 feet, and to go to 150 feet (the depth of the highest point of the mine), he needs a 12-ton crane which Sen has. Dayal asks Sen to give the crane to Jaswant. To ruin this attempt, Sen has key pieces removed from the crane he brought in, preventing the miners from being speedily rescued. Gill explains the capsule to Natarajan and volunteers to go down to the miners to supervise the rescue operation himself. But Sen insists that his rescue officers will handle the rescue. The officers abandon their post calling Sen a coward. Gill proceeds with his original plan. With no alternative, they begin manually winching each miner out. Most of the miners are rescued, but in a critical phase, oxygen runs low, and they realize they cannot save everyone manually.Govardhan, the local MLA and union leader, attacks Sen until he admits to deliberately ruining the crane. Under pressure, he has the crane fixed and brought to the mine. Gill appears to black out from lack of oxygen, but despite losing his metal hammer (striking 3 times would signal to the surface that the capsule must be pulled up), uses his Kara to signal the capsule to be lifted.Gill is the last to be removed from the minefields and is rewarded with a Rs. 1 Lakh check and immediate promotion. The disgraced surveyor is recognized for his efforts and paid his missing wages.