Scenario of destruction and progress continues in this fourth part once again narrated by Michael Fenton-Stevens. People of Datum continue to step on more and more earths but this time the heroes are not there to look after them or protect them. After many years of tough and hard work the heroes have finally grown old and they are not in mode of performing what they used to like in their youth.
Lobsang the first one to go down tries to mix in the common people where his aim is to keep a low profile. Joshua was first worried about his married life in The Long War and The Long Mars but now he is looking for his father. Joshua too is not a vibrant youth anymore but the family history that he finds out is enough to charge him up once again. Since the time when the Long Earth was discovered there was a competition between the human races but not heavy fights.
The human race just kept on occupying the planets that they stepped on to but here the Long Earth just gets connected with the wrong planet. An alien race has come to know about human colonies and now it wishes to capture everything that has been in the grasp of the humans.
Terry Pratchett first creates a utopia at the start of this novel and then with the emergence of the alien race the utopia suddenly vanishes in thin air. Mankind though that the worries were over forever but they just collide with the biggest worry of the millennium with the discovery of the alien world.