65 Million years ago an extraterrestrial craft came and took willing species of dinosaurs to a planet to ensure their survive throughout the ages. It's a secret that a budding science-fiction writer soon finds out as a solo, early morning fishing expedition finds him pulling a prehistoric fish, one who was alive right before the extinction of the dinosaurs, out of the Florida waters where he is vacationing. Soon he calls upon his grandfather and his crew of intellectuals, all of whom have a shared loved of prehistory and especially of dinosaurs, and they comb the waters for any more of these beasts. It's not long before they encounter a U.S.O., Underwater Submerged Object, and find themselves on the Planet of the Dinosaurs themselves.