 Why are there three women and one man in the home?
If it only had a lease that could be broken— Roger Tennant, crossing the lawn, could see two of the three wings of the house, which radiated spoke-like from its heptagonal central portion. They entered the house, which had no roof, continued to move beneath a sky that glowed with light which did not come from a sun or moon. It arrived before the meal, materializing against one of the seven walls of the roofless chamber. He had felt the inner tug of command, said good-by to the women and returned to his smaller compound within its own barrier dome. As in all of this strange universe, excepting the dome-cages in which the captives were held, the training hall followed no rules of three-dimensional space.
 they were the only people the aliens had been able to bring back alive
 the other captives had killed themselves before this  they wanted extra women to make more babies  it's the correct number they want for their social experiment  they were the only people the aliens had been able to bring back alive