On March 11, 2011, a magnitude-nine earthquake off Japan's coast sends a tsunami crashing into the Fukushima Daiichi nuclear plant, knocking out its cooling systems and triggering the worst nuclear accident since Chernobyl. The film reconstructs the disaster hour by hour, using plant data, control-room accounts, and interviews with the engineers and nuclear specialists who scrambled to understand what was happening inside reactors they could no longer see into. It follows the workers who stayed behind to vent radioactive gas and pump seawater into overheating reactor cores, the government officials weighing evacuation zones as radiation readings climbed, and the outside experts trying to figure out from a distance whether a full meltdown was already underway. Footage of the plant's hydrogen explosions is paired with technical breakdowns of exactly what failed and why, from backup generators flooded by the tsunami to the fuel rods left exposed once cooling stopped. The film treats the accident as a case study in how a natural disaster becomes a technological one.