Charlton Heston is the powerful, brooding owner of a plantation in the wild and treacherous South American jungle. Eleanor Parker is his charming American mail-order bride. But Heston is wary of the beautiful and talented Parker, and wonders why she would leave America for the rigors of jungle life. They're both threatened by the advance of billions of relentless killer ants who are making their way across the jungle-cutting a path of creeping horror which is 20 miles long and 2 miles wide.