A party of astronauts on a mission to Mars discovers evidence that the red planet once sustained life, but soon after one of their number is killed. As further deaths occur, the explorers realise the organisms they have found may still be alive and could kill them all. Sci-fi horror, starring Liev Schreiber, Elias Koteas and Romola Garai.

On the last day of the first manned mission to Mars, a crew member of Tantalus Base believes he has made an astounding discovery – fossilized evidence of bacterial life. Unwilling to let the relief crew claim all the glory, he disobeys orders to pack up and goes out on an unauthorized expedition to collect further samples. But a routine excavation turns to disaster when the porous ground collapses and he falls into a deep crevice. His devastated colleagues attempt to recover his body. However, when another vanishes, they start to suspect that the life-form they have discovered is not without danger.