Book I, Chapter 3: "Three is Company"
Although Gandalf wonders in passing if Frodo will eventually have to travel to the Cracks of Doom in Mordor, he advises that the Hobbit go to Rivendell, the peaceful valley in which Elrond and other Elves make their home. Frodo sells Bag End to Lobelia Sackville-Baggins and her son Lotho, relatives whom Bilbo had always loathed. Frodo acts as though he is moving to settle in Crickhollow, on The Shire's eastern borders. Gandalf departs the Shire, hoping to return in the fall before Frodo leaves. He does not.

On their way to Crickhollow, Frodo, Sam, and Pippin must hide from a rider, shrouded in black, who seems to be seeking them. (This rider will not be the only one the Hobbits encounter in Book I; throughout, they refer to their mysterious pursuers as "Black Riders," as will these notes. Only later do the Hobbits learn that the Black Riders are the Ringwraiths of whom Gandalf spoke, the nine mortal Men who long ago became enslaved to Sauron.) While hiding from the Black Rider, Frodo successfully fights the urge to wear the Ring. When the Black Rider moves on, Sam remembers that his father ("the Gaffer") had been accosted by a Black Rider looking for "Mr. Baggins."

After avoiding another Black Rider-and after Frodo must struggle even more to resist wearing the Ring-the three Hobbits encounter Elves. According to one of them, Gildor, these Elves are preparing to leave Middle-earth, and will sail west, over the Great Sea. The Elves tell Frodo that they know he is leaving the Shire, and that he is being pursued by the Black Riders, but they do not know why.