On the final day of the primary manned mission to Mars, a crew member of Tantalus Base believes he has made an astounding discovery – fossilized proof of bacterial life. Unwilling to let the aid crew claims all of the glory, he disobeys orders to pack up and goes out on an unauthorized expedition to gather additional samples. However a routine excavation turns to catastrophe when the porous floor collapses and he falls right into a deep crevice and close to sure demise. His devastated colleagues try to get well his physique. Nonetheless, when one other vanishes, they begin to suspect that the life-form they’ve found is just not with out hazard.