There is a planet in another solar system called Xerios, where it seems that the Earth mirrored itself in it, in the sense that all the things of that planet are identical to the things of the Earth and identical also, are their skies.
For every river on Earth, there exists an exact one on that planet. For every mountain there exists an identical one, identical cities, identical blades of grass, and even identical men.
For each man on earth, there corresponds an identical one on that planet, a man exactly like him, with the same family tree, the same face, the same brain.
The only difference is in the fact that for fifteen years, the men of that planet have seen their desires fulfilled.
It so happens, that a group of Earthlings coming from the most varied social environments, find themselves hurled on Xerios, thinking they are on Earth, and many of them meet their corresponding lookalikes.