Ukraine, April 26, 1986. The nuclear power plant near Chernobyl is due for routine tests. The tests are to check if it can be restarted independently after a total outage of the electricity network. Foreman Anatoli Diatlov is supervising tests on reactor number 4. Confident in his equipment, Diatlov decides, against the advice of his engineers, to push the reactor tests to the limit and disables several security measures. When the team notices the reactor is overheating, they trigger the alarms. But it’s too late: reactor number 4 goes into irreversible meltdown and explodes, sending dozens of tons of radioactive steam into the atmosphere. When firefighters arrive on the scene, they manage to extinguish all the fires except one: reactor number 4 is out of control. Its core is now magma in fusion, threatening at any moment to pour onto the tons of water pumped by the firefighters. That would provoke a nuclear cataclysm that would destroy Central Europe. Three volunteers agree to sacrifice their lives. They return to the plant, open the valves, release the water and thus save the world from nuclear disaster. The Chernobyl disaster is the most serious ever recorded on our planet: a nuclear accident that is 7 on a scale of 7. Its effects on people and the environment are still being felt today as a new confinement shelter has just been built to contain the disaster for another 100 years. However, the consequences of this tragedy could have been far more horrific but for the heroism of three of the plant’s workers.