The Tolkien novel that introduces Bilbo Baggins’s adventure with the dwarves is The Hobbit. Its full title is The Hobbit, or There and Back Again, and George Allen & Unwin first published it in 1937.
The story begins when the wizard Gandalf and thirteen dwarves arrive at Bilbo’s home in Hobbiton. They recruit him as a burglar for an expedition to the Lonely Mountain, where the dragon Smaug guards the dwarves’ treasure and former kingdom.
The Hobbit predates The Lord of the Rings and was originally written as a children’s fantasy adventure. It introduces characters and objects that later become central to the larger story, including Gollum and the One Ring. Although later editions were adjusted to fit the developing mythology, the novel remains a complete adventure in its own right.