A secret mission on the surface of Mars leads to a cosmic struggle between a dwindling team of space explorers and an unknown life form. The crew of the Tantalus Base is wrapping up the first manned mission to Mars when one astronaut discovers fossilized evidence of bacterial life. Determined to get credit for the historic find, the astronaut defiantly ventures out to collect more samples despite strict orders to remain on the ship. When the ground seems to swallow him whole, the remaining crew launch a rescue mission that leads to yet another mysterious disappearance. Meanwhile, with the relief ship Aurora drawing near, it begins to appear as if the life form discovered by the Tantalus Base crew is far from dead, and should it somehow find its way back to planet Earth, humankind's days could be numbered.