Bilbo Baggins awakes late the next morning to find that the dwarves are gone. Gandalf appears and shows him a note the dwarves left, agreeing to give him one-fourteenth of the profits if he accompanies them to reclaim their treasure. Bilbo runs to meet the dwarves, forgetting his handkerchief.
Bilbo and the dwarves set off on ponies loaded with provisions; Gandalf soon joins them. They ride first through friendly hobbit-lands, but the journey becomes unpleasant by the end of May, as they ride far into the uninhabited Lone-lands. Riding in the rain, Bilbo wishes he were back at home. Gandalf disappears, and one of their loaded ponies runs away, leaving them with little food.
The hungry group is trying to make camp in the wet forest when they see a light and send Bilbo to investigate. He finds three trolls — Bert, Tom, and William — around a fire, roasting mutton and complaining of having no men to eat. Bilbo, trying to act like a burglar, is caught trying to pick William's pocket. The trolls disagree about what to do with Bilbo and are fighting among themselves when Balin enters their camp. They capture him and put him into a sack, and then do the same to the rest of the dwarves who come looking for Bilbo. Bilbo hides in the top of a bush.
Gandalf returns and tricks the trolls into staying out past dawn and they turn to stone, because trolls must be underground during the day. Gandalf and Bilbo free the dwarves. They find the trolls' secret cave and help themselves to food, clothes, swords, and gold coins, and then they go to sleep.
The next morning, they load their ponies. They bury the gold for safekeeping and continue to travel east. Gandalf tells Thorin that he had been scouting ahead when he heard in Rivendell that trolls were in the area and he knew he was wanted back. He warns Thorin to take care.
Bilbo begins this important journey without the sense of purpose that the dwarves have. He awakens late and the fact that the dwarves have already left allows him to second guess the commitment he made the night before and revert to his comfort-loving hobbit ways. Bilbo's worry that he has forgotten his handkerchief is a last remnant of his hobbit life; after he begins his journey with the dwarves, such concerns seem irrelevant. It is significant that the dwarves agree to give Bilbo a share of the treasure they will reclaim, because greed is a dwarvish trait and they have difficulty sharing.
Gandalf continues as a tutelary figure in this chapter. His role is to impart wisdom, directing Bilbo to realize his potential on this journey. He drives Bilbo into honoring his agreement with the dwarves despite his misgivings. Gandalf shows up unexpectedly at Bilbo's house and disappears later in the chapter. He continues throughout the journey to appear and disappear almost without warning, an indication of his powers.
You begin to get some sense of the geography of the journey to the Lonely Mountain as the group passes through hobbit-lands and Lone-lands. As they travel east and approach the Lonely Mountain, the way becomes increasingly difficult and the landscape becomes bleaker and less familiar.
The group begins, in this chapter, to experience the discomforts that will grow into real perils and trials by which they are tested. Rain, cold, and hunger are typical of these discomforts. Bilbo is sent into the group of trolls to investigate, foreshadowing the many times he will investigate — and be pushed beyond his customary limits — on the journey, and his attempt to steal from William's pocket is an effort to justify his role of burglar. Likewise, the trolls' capture of the dwarves foreshadows several instances of the dwarves victimization at the hands of their enemies; in future instances, Bilbo or Gandalf continue to rescue them. Gandalf's trickery of the trolls is typical of his dealing with enemies: Gandalf does not use violence nearly as often as he outwits his opponents.
The trolls are another group of fantastical creatures, like the hobbits or dwarves, but far more threatening. The fact that they turn into stone in the daylight adds to the fantasy quality of the story. Bilbo and the dwarves' discovery of food, clothing, weapons, and gold in their cave is fortuitous, and the weapons soon assume greater meaning.