A spacecraft is discovered at the bottom of the Pacific Ocean, presumed to be at least 300 years old and of alien origin. A crack team of scientists and experts is assembled and taken to the ocean floor to investigate. However, the ship is not as it seems and when a giant perfect sphere is discovered in the cargo bay, things begin to fall apart.
During the Vietnam War, a recon unit ventures to an isolated jungle valley to uncover the fate of a missing platoon. They soon find themselves in a fight for their lives against an unexpected enemy — prehistoric dinosaurs.
Set in the future, the story follows a young soldier named Johnny Rico and his exploits in the Mobile Infantry. Rico's military career progresses from recruit to non-commissioned officer and finally to officer against the backdrop of an interstellar war between mankind and an arachnoid species known as "the Bugs."