A deep-sea submarine is attacked by a giant and dangerous creature long believed to be extinct. As a result, the entire group was trapped at the bottom of the Pacific Ocean and their lives were in danger. As time passed, a team of expert divers headed by Jonas Taylor, a Chinese oceanographer, and his niece Suyin arrived to rescue the ship. But no one expected that their enemy would be the largest and greatest predator in history - a 75-foot-long prehistoric shark commonly known as Megalodon.