An international scientific research project led by China was being carried out in the depths of the Mariana Trench when it was attacked by an unknown creature and the researchers were trapped on the seabed. Jonas Taylor, a former deep-sea diving expert of the US Marine Corps, was ordered to rescue them and once again encountered the prehistoric creature Megalodon, which had left him with an indelible memory for a lifetime in the deep sea several years ago. Jonas teamed up with Zhang Suyin, a Chinese female scientist in the scientific research project, to successfully rescue the trapped personnel, but the rescue operation accidentally caused the Megalodon to escape from the deep sea. When the prehistoric monster returns to the shallow sea, humans will pay a heavy price for their greed for nature...