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, Part Two; 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.