The book starts with the most complete version of the beginning of the tale, "The Tale of Tinúviel" as told in
The Book of Lost Tales, with only slight editing of character and place names to avoid confusion with later versions. The general aspect of the story has not been modified; Beren, for example, is a Gnome (Noldo), the son of Egnor bo-Rimion, rather than the human son of Barahir. Beren's heritage switches between elf and man throughout the book, depending on which portion of the story is being told. As Christopher Tolkien explains: Further chapters continue the story through later poems, summaries, and prose, showing how the story evolved over time, in order of the chronology of the story itself (not necessarily the order in which the texts were written or published). These include portions of various versions of "The Lay of Leithian",
The Silmarillion, and later chapters of
Lost Tales. Since J. R. R. Tolkien made many changes to the story, affecting both narrative and style, the presentation in the book is not entirely consistent. There is some overlap of details and discrepancy in continuity, but the sections attempt a complete and continuous story. Christopher Tolkien included editorial explanations and historical details to bridge between sections. Details lost in later accounts were reintroduced: such as
Tevildo (who due to the nature of his introduction is treated as a separate character, rather than an early conception of
Sauron), Thû the Necromancer (treated as the first appearance of Sauron), the Wicked (or "treacherous") Dwarves (one of
The Hobbits references to
Lost Tales), and other terminology such as Gnome (Noldoli, later
Noldorin Elf),
Fay,
Fairy, leprechaun, and pixie. Some of these terms appear in early editions of
The Hobbit, but were dropped in later writing. The book offers an "in-universe" perspective for the inconsistencies, as owing to the evolution of the stories told by different perspectives and voices over time, rather than simply reflecting Tolkien's changing ideas over time. This book reintroduces details that were omitted in
the highly edited version of ''The Silmarillion's "Of the Ruin of Doriath": it includes the cursed treasure of Mîm; that Doriath was betrayed from the inside; that Thingol was able to push the dwarves out of the city; and that he was later killed by an ambush of dwarves. It roughly reconciles the elements of early Lost Tales
with details constructed by Guy Kay for the chapter in the Silmarillion'', to bring it closer to Tolkien's intention as described in
The War of the Jewels: == Analysis ==