The Fall of Númenor collects already-published materials about the Second Age of Middle-earth into a chronological format, its structure exactly mirroring the timeline supplied by J. R. R. Tolkien in "A Tale of Years" in Appendix B of The Lord of the Rings.

The body of the book, titled "The Tale of Years (Chronology of the Westland)s", covers the foundation, history and destruction of the land of Númenor; the forging of the Rings of Power; and the Last Alliance against Sauron that ended the Second Age.

[2] Given that it was released at the same time as Amazon's Rings of Power, Danehy-Oakes remarks, it offers fans a view of the feigned history of the Second Age, without what he calls the "distort[ions] and misrepresent[ations] of the television series.

[4] Kane notes that Sibley uses Tolkien's "The Tale of Years"[5] as his framework, supplying the titles of his chapters, and then "attempt[ing] to pigeon-hole excerpts" from all the sources he employed under those headings.

"[4] He quotes Eldy Dunami's view of the book's use of the tale of Aldarion and Erendis, which she calls "the most egregious example" of cutting up a story and interleaving the excerpts with fragments from other places.