The Penultimate Truth follows people living in underground shelters, for fear of a World War III that they are told is being waged on the surface above them. We could go into more of the similarities between the book and Bethesda's Fallout 3, but then that would mean venturing into dangerous, radiation-strewn spoiler territory.
Of course, if one wants to say that Bethesda plagiarized The Penultimate Truth, then one must look to previous titles in the Fallout series, as well. Vaults were featured in previous games, and upon exiting these vaults, hubs of civilization were also found among what was thought to be a post-apocalyptic barren wasteland. So does that mean Interplay plagiarized The Penultimate Truth or that, perhaps, the idea isn't entirely unique in the first place?