Many, many years before, when Bilbo was young and courageous, he had set off on a treasure hunt with Gandalf the Wizard and a company of Dwarves. During several hair-raising adventures, whilst escaping from a Goblins' cave, Bilbo fell down a hole and was separated from his companions. Groping his way down a murky tunnel, he felt a ring between his fingers and put it in his pocket. Gollum, the cave dweller, an unpleasant and slimy creature, decided to play with the Hobbit by asking him riddles. If you win, Gollum whined, I will show you the way out, and if you lose, I will eat you. Bilbo failed the test and in his nervousness, slipped on the ring, the One-ring, and became invisible; thereby making his escape.