The Martian civilization is nearly at an end. Only two Martians have survived the eons. Their physical shortcomings prevented them from colonizing other worlds, and now their species will become extinct.
When Martians die, they dissolve into dormant microbes that still live in the Martian soil.
A powerful asteroid hits the Red Planet, ejecting billions of tons of microbe-laden soil straight towards Earth, coving the planet.
99% of the population dies by the next day.
Four nurses meet up with a group of four doctors. They head to an underground military base on a mission. We don’t know yet why these eight people (at least, for now) are immune to the microbes.
All the soldiers in the underground base die from the supposedly beneficial injection.
The doctors and nurses decide to stay there long enough to figure out how to best help whatever survivors are still out there.
The doors leading outside malfunction. The group is trapped in the underground base.
Occasionally, the doctors act weirdly. Not quite human. They’re becoming a Human/Martian hybrid.
Although the doctors are slowly becoming Martian, their outward physical appearance only changes when they are engaged in some pursuit requiring concentration. The women try to explain away the doctors’ occasional weird behavior as eccentricity.
The doctors want to procreate with the nurses to proliferate their new species. The four women must escape.
The women learn that the doctors’ Achilles heel is that they become trapped in a type of “hive mind” when tough mathematical equations and unanswerable, complex scientific questions are posed to them.
The women escape by using this Martian/Human flaw against them. The doctors, now a pitiful hybrid of Human/Martian, are unable to break free from their hive mind, and die inside the bunker.