The Cyclops.

Test pilot Bruce Barton (Duncan Parkin) is missing and his girlfriend, Susan Winter (Gloria Talbott) organizes a search party, sent out in the jungles of Mexico. The team of scientist Russ Bradford (James Craig), mining expert Martin "Marty" Melville (Lon Chaney Jr.) and pilot Lee Brand (Tom Drake) fly into an unknown territory. While searching the area, they uncover giant mutated earth animals such as giant snakes, lizards, behemoth bugs and oversized mammals.