J.R.R. Tolkien's latest posthumous book may actually be the last.

The publication of "The Fall of Gondolin," at long last, represents the conclusion of a loose trilogy set in the Elder Days of J.R.R. Tolkien's fictional realm of Middle-earth. As with the posthumously published "The Children of Húrin" and "Beren and Lúthien," this entry has been painstakingly and, clearly, lovingly edited by his son and literary executor Christopher Tolkien. Taking place long before the events of "The Hobbit" and "The Lord of the Rings," the books fill in the historical record of those better-known stories. The present volume collects several drafts from Tolkien's vast archive. A helpful essay explains how the story changed over the years. In short, the evil overlord Morgoth - called Melko here - seeks to dominate the entire world, but the hidden elvish city of Gondolin remains out of his grasp. Readers of "The Silmarillion," also edited by Christopher Tolkien and published posthumously, will recognize Morgoth. For the sake of context, Sauron - the villain in the "The Lord of the Rings" - is one of his henchmen. [ABSTRACT FROM PUBLISHER]