Early 20th-century adventurers find themselves fighting for survival after their hot-air balloon crashes into a remote part of the Amazon, stranding them on a prehistoric plateau.

A group of unlikely allies are assembled to go on an expedition deep within the Amazon forest in search of new discoveries.

Mysterious deaths and unexplained disappearances begin to occur in the small seaport village of Graves Point. When a large, strange claw is discovered on an empty raft washing up on the shore, marine biologist Dr. Herbert Talley identifies it as belonging to a rare giant squid.