The US military is running a test for a special type of radio transmitter, to be used to communicate with submarines, in a deep system of caves in Central America.

Exploring deep underground, they stumble upon a tribe of albino cave-dwellers who have apparently been isolated from the rest of the world for thousands of years.

"[8] Production was briefly halted in late August when carbon monoxide produced by generators in the Cathedral Caverns location sent at least 17 people, including Sharp, to the hospital.

[7][9] Blount recalled the accident happened while her character was captured and tied up on a rise inside the cavern.

"All the extras, as the Lemurians, were out in front of me, and I watched all these people just start silently falling over, fainting, as this wave of carbon monoxide came at them," she said.

[10] Co-producer and special effects designer Robert D. Bailey said "Frankly, I underestimated the difficulty of shooting in the caverns.

Sharp said he told the producer he felt the film was awful and he left after shooting without taking part in editing.