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 Manwë, chief of the Valar.

Central to this enmity of the
gods is the city of Gondolin, beautiful but undiscoverable. It was built
and peopled by Noldorin Elves who, when they dwelt in Valinor, the land
of the gods, rebelled against their rule and fled to Middle-earth.
Turgon King of Gondolin is hated and feared above all his enemies by
Morgoth, who seeks in vain to discover the marvellously hidden city,
while the gods in Valinor in heated debate largely refuse to intervene
in support of Ulmo’s desires and designs.

Into this world comes
Tuor, cousin of Túrin, the instrument of Ulmo’s designs. Guided unseen
by him Tuor sets out from the land of his birth on the fearful journey
to Gondolin, and in one of the most arresting moments in the history of
Middle-earth the sea-god himself appears to him, rising out of the ocean
in the midst of a storm. In Gondolin he becomes great; he is wedded to
Idril, Turgon’s daughter, and their son is Eärendel, whose birth and
profound importance in days to come is foreseen by Ulmo.

At last
comes the terrible ending. Morgoth learns through an act of supreme
treachery all that he needs to mount a devastating attack on the city,
with Balrogs and dragons and numberless Orcs. After a minutely observed
account of the fall of Gondolin, the tale ends with the escape of Túrin
and Idril, with the child Eärendel, looking back from a cleft in the
mountains as they flee southward, at the blazing wreckage of their city.
They were journeying into a new story, the Tale of Eärendel, which
Tolkien never wrote, but which is sketched out in this book from other
sources.