In the Tale of The Fall of Gondolin are two of the greatest powers in the world. There is Morgoth of the uttermost evil, unseen in this story but ruling over a vast military power from his fortress of Angband. Deeply opposed to Morgoth is Ulmo, second in might only to Manwe, chief of the Valar.
Following his presentation of Beren and Lthien Christopher Tolkien has used the same 'history in sequence' mode in the writing of this edition of The Fall of Gondolin. In the words of J.R.R. Tolkien, it was the first real story of this imaginary world and, together with Beren and Lthien and The Children of Hrin, he regarded it as one of the three 'Great Tales' of the Elder Days.