Book I, Chapter 6: "The Old Forest"
The Hobbits leave Crickhollow and enter the Old Forest, where the trees themselves hinder the company's progress-one example among many in The Lord of the Rings of Nature expressing a will of its own. The atmosphere in the Old Forest proves so oppressive, Frodo is not able even to sing to encourage his companions. Eventually, the Hobbits lose all sense of direction. They emerge from gloom by the Withywindle River, whose valley is said to be "the queerest part of the whole wood-the centre from which all the queerness comes, as it were." They find a path by the River, but do not know who or what has made it. As they follow the path, sudden and irresistible weariness overtakes them all. The Hobbits fall asleep by the branches of a large willow.
Sam awakens first, only to find that the willow tree has swallowed Pippin, has trapped Merry in a crack, and has tossed Frodo into the Withywindle. Sam and Frodo attempt to release their friends by lighting a fire to threaten the tree, but the fire succeeds only in angering it, thus putting Merry and Pippin at greater risk. In desperation, Frodo calls for help-and receives a response from an odd man in colorful clothes called Tom Bombadil. Tom, who calls the tree Old Man Willow, literally sings the Hobbits out of its grasp. Tom invites the Hobbits to his home for a meal, which invitation the Hobbits gratefully accept.