A treasure hunter, Jackson Slate, is out to find the lost gold treasure of Cortez in the open waters of Belize. He is out to pay off his debts from gangster Tariq. While scuba diving, his team sets off rounds of dynamite that awaken a prehistoric monster from the depths of the blue hole. Jax is saved by a young couple, Rod and Jane, vacationing on a diving boat.
He wakes up with the two kids, and meets the local dive boat operator Henry, and marine biologist Sarah. Jax shows them the gold coin he found and talks about the monster they encountered. He realizes he is the only lone survivor from the accident. Sarah, intrigued by the creature agrees to help him.
They go back and retrieve one of the eggs to examine it and realize they are dealing with a prehistoric dinosaur species that has been undiscovered. The egg is cracked open and a small dinosaur is unleashed wrecking havoc throughout the laboratory. Meanwhile, the P Rex predator terrorizes and destroys a party boat, killing all the kids on board and knocking Jane into the water. Rod dives in to rescue Jane but cannot save her. The P Rex heads toward shore and stomps throughout town killing everyone in sight.
Meanwhile Sarah and Jax run off in hopes of stopping the creature from destroying the town. They head for the local military base and contact the troops for help. Just as the monster heads their way, Sarah and Rod jump into a boat and shoot off missiles at P Rex while Jax charters a military jet and aims target for the creature. Sarah gasps in horror as the Cessna jet plane fades into the white explosion of the hit at the creature. There is no sign of Jax to be found. Then suddenly, our hero finds his way onto her boat from the water. Sarah wraps her arms around him, and they live to see another day.