Humanity has discovered a unique solution to its overpopulation problem by finding a means of traveling to alternate-history Earths. Simply find an Earth which never developed life, and stick one house with one family on it—and then everybody gets a whole planet to themself. Not everybody is quite sanguine about the situation, however, and when one alternate Earth proves to be housing a colony of Nazis from yet another alternate Earth, it proves to be the prelude to something very much different.
You know, I just now got the pun in the title. Sigh.
The idea of travel between alternate Earths is hardly a new one in science fiction, but I must admit that this is one of the few stories I’ve ever read that has anything to say about the practical uses for such a technology. Most alternate-Earth stories are, of course, alternate histories, where we get to see our favorite historical figures in unexpected situations. As with The End of Eternity, however, Asimov here takes an overused sf cliche and turns it on its head by approaching it from a direction I have never encountered elsewhere.
As with many stories by the Good Doctor, the characters here are secondary and forgettable. The situation and ideas underlying the tale, however, are fascinating, as are the consequences of the technology herein described. Definitely a strong story deserving more circulation than it gets.