On May 22, 1960, an earthquake with an intensity of 9.6 on the Richter Scale was recorded in the city of Valdivia, considered to date the largest and most violent earthquake ever recorded in the world. The cataclysm devastated the entire Chilean territory between Talca and Chiloé, which corresponds to more than 400,000 km. It resulted in the deaths of around three thousand people, while two million were left homeless. The film documents the efforts of a hundred workers in the face of the threat of the overflowing of Lake Riñihue.