J.R.R. Tolkien's ''Unfinished Tales'' is a collection ranging from the time of ''The Silmarillion'' the Elder Days of Middle-earth to the end of the War of the Ring in ''The Lord of the Rings''. Its many treasures include Gandalf's lively account of how he came to send the Dwarves to the celebrated party at Bag-End, the emergence of the sea-god Ulmo before the eyes of Tuor on the coast of Beleriand, and a description of the military organisation of the Riders of Rohan. Lovers of Tolkien's mythology will also be fascinated to read the only story from the long ages of Numenor before its downfall, and all that is known of such matters as the Five Wizards, the Palantiri, and the legend of Amroth. The collection has been edited by Christopher Tolkien, who provides a commentary placing each of the Tales in the context of his father's work.