The book compiles material previously published elsewhere, namely "The Tale of The Fall of Gondolin" and "Isfin and Eöl" both published in the Book of Lost Tales II; "Turlin and the Exiles of Gondolin" published in "The Shaping of Middle-earth"; excerpts from the "Sketch of the Mythology" and "Quenta Noldorinwa", both published in "The Shaping of Middle-Earth"; and "Of Tuor and The Fall of Gondolin" published in "Unfinished Tales", along with excerpts from "The Silmarillion" and elsewhere.