In a faraway place in a faraway past, a radiation blast sterilised every member of the smarter sex of the colonisation expedition merely moments after landing. Using genetic engineering and biotechnology trickery the settlers survived, though only two of the three sexes remained: the fairer sex and the stronger sex. Presently, there’s no memory left of the third sex, and the members of the other two do not imagine the possibility of its existence, though nothing else explains the fact that they’re so messed up and incompatible to each other.
Tomorrow, a space vehicle will appear in their skies, carrying a second expedition, a rescue mission consisting of all three sexes, looking for their lost brothers and sisters. “Take us to your leaders,” every communication device will coo, moved by a deep desire to set things right as quickly as possible in that tormented place. A very predictable turmoil will ensue, with celebrations and demonstrations and knock knock knocking on heaven’s door, and forty five dark pieces of metal in orbit will turn quietly towards the messengers and will cover them softly with an atomic fire brighter than the sun.
And thus it will turn out that the smarter sex isn’t smart enough, and that the other two will stay hopelessly irrevocable.