A group of treasure hunters searching for a legendary treasure in the Caribbean Sea accidentally awaken a prehistoric creature known as Poseidon Rex. As they struggle to survive and escape from the creature's wrath, they face various challenges and dangers including military interference, a party boat filled with traffickers, and the unpredictable nature of the creature itself. Will they be able to find the treasure and make it out alive, or will the Poseidon Rex become their ultimate demise?

An alien life form comes to Earth to help a young couple save their unborn child from the Darkside.