Before the the War of the Ring, the Palantir stones of Annuminas and Amon have been discovered. You are recruited by Gandalf and Aragon to hide the Palantir stone that none will use it. Rival clans of elves, Sauron's forces, and most of your selfish ambitions stand in the way of your quest.
From the back cover:
The Battle of Five Armies is long past, but the War of the Ring has yet to ravage Middle-earth. During this dark period of uneasiness, tension grows between the Free Peoples of Endor. When it comes to light that the last Seeing Stone of the North has been recovered, its power proves tempting. Now the Free Peoples race against each other and the minions of the Witch-king of Angmar to seize this great treasure for themselves. YOU are sent by Gandalf and Aragorn on an exciting and dangerous search in this, the fourth gamebook of the MIDDLE-EARTH QUEST(TM) series!