The first mission to Mars crashes onto the surface of the planet. The astronauts are faced with a dire situation. With no resources and no time to wait for the rescue team to arrive, they have just one alternative: three must die so two can survive. But who will live and who will die? The story takes us, with the details of a documentary, on the adventures of the three crew members (Susana, Herbert and Rodrigo) who decide to die to let their team-mates survive. They cover the distance separating them from Marineris Valley and descend into its depths, where they find hidden beneath a permanent layer of fog, a great mystery about the planet's distant past - and a chance of survival for the castaways on Mars.