The Missing Rider
The following story can be experienced by starting the quest "Book 4, Chapter 1: Where is the horse and rider?".
No sooner had the heroes reached Rivendell that they found themselves departing it. They made for Thorenhad, the encampment led by the sons of Elrond within the Trollshaws. Their mission was clear; locate the ninth black rider.
Elladan and Elrohir had tracked the Nazgûl towards the southern Trollshaws. The ruins within the narrow channels, called Minas Agor, had a fell reputation and the Nazgûl may have sought it out for that reason.
The pass was full of Cave Trolls and Hillmen. The heroes fought bravely through the ruins until they came upon a dead stead. It was clear that the horse had belonged to the missing Nazgûl.
Elladan and Elrohir believed the Nazgûl had survived the attack at the Ford of Bruinen. Without its horse and cloak, however, the Nazgûl would be all but invisible. They tasked the heroes with consulting Lord Glorfindel on how to find the missing rider.
Glorfindel provided the heroes a small beryl to hold aloft within the Ford of Bruinen. The nine, servants of the Enemy, were creatures of such evil that the land could not bear their presence. The beryl would glow in places where they had been. With this, they would be able to track the missing rider.
The heroes, at Elladan’s suggestion, made for secluded caves within the Trollshaws in search of the Nazgûl. The heroes searched far and wide for the Nazgûl, but found no sign of them. During their search, news had reached the sons of Elrond that Barachan had spotted an Onodrim. Believing it could be of help in tracking the Nazgûl, the heroes made for Barachan’s camp.
Barachan told of his adventure within the High Moor near Rivendell. While seeking out his fellow scouts, he witnessed a great Onodrim. Barachan had heard stories of the Onodrim and tasked the heroes with seeking it out.
The heroes found the Onodrim deep within the High Moor but unfortunately the stories had proven false as the wood troll enraged and attacked them. Elladan, upon hearing this news, could not believe an Onodrim would ever attack a free person. He told of a small company of elves from Mirkwood that had arrived at Rivendell to consult with Lord Elrond. They would know what manner of creature the heroes had faced...
Legolas, son of Thranduil, told of Wood-trolls and believed that is what they had faced in the High Moor. Together, they sought out to find their lair and discover the source of the evil. Deep within the troll lair, they encountered the Nazgûl and the Wood-troll leader.
With the Wood-troll defeated, and the Nazgûl dispersed, Legolas and the heroes returned to Rivendell. Elrond was glad to hear the Nazgûl was driven from the Trollshaws, but it was likely it would focus its attack upon Rivendell from the north and east. It would be necessary for the heroes to make for the Misty Mountains. Aragorn, however, first had a request from the heroes to assist him in a momentous task...
Further Reading: Into the Misty Mountains & A Momentous Decision