This eventful day starts badly for Bilbo. As we discover later, Gandalf's magic has enabled the others to escape the goblins, but Bilbo is accidentally left behind, unconscious on the tunnel floor. On waking, he crawls around looking for a way out.

And then he finds the ring.

In fact, his hand "meets" it - has the ring chosen a new owner? "It was a turning point in his career, although he did not know it" - Tolkien is talking about Bilbo but this applies equally to himself.

For a while Bilbo despairs. Then, heartened by the idea that his sword was forged in Gondolin, he continues through the darkness and finds Gollum - a small, dark, slimy creature living near an underground lake, who will eat him - given the chance! Trapped, Bilbo makes a pact with Gollum: they will trade riddles. If Bilbo wins, Gollum shows him the way out. If he loses, Gollum eats him . . .

Tolkien's children would have recognised Bilbo's riddles, which are drawn from popular fairy tales, while Gollum's go back to Anglo-Saxon times. Tolkien is amusing himself here by incorporating oral tradition, having already called his "rabble of Eddaic-named dwarves*" after characters in the Norse saga Völuspá - and 'Gandalf' means 'elf with a staff' (gand-aelf)**.

As the riddles get harder, Bilbo panics; he guesses the last one by "pure luck" (Bilbo has a lot of "luck" throughout his adventures, which suggests that fate is at work). Unable to think of another, he absent-mindedly touches the ring and cries "What have I got in my pocket?". Gollum thinks it's part of the game, and is stumped. There is no cheating - this is a children's story!

Reluctantly Gollum agrees to show Bilbo the way out, secretly planning to use the ring - which he doesn't realise he's lost - to become invisible, and kill Bilbo. Of course, he can't find it, and,suspecting the truth, attacks. Bilbo flees, the ring slips onto his finger, and he discovers that he can follow Gollum to the exit without being seen. Gollum, talking wildly to himself, veers between searching for the ring and luring Bilbo back to the goblins. Yet Bilbo pities Gollum and chooses not to kill him before escaping. Shippey** points out that Bilbo empathises with Gollum because he has far more in common with him than he does with the dwarves . This display of mercy, along with the discovery of the ring, has great significance for the future of Middle-Earth.

Bilbo catches up with Gandalf and the dwarves, but when they swap escape stories, Bilbo decides not to mention the ring. They resume their journey but are forced to climb trees to escape wolves. Gandalf bombards the wolves with flaming pine cones, which attracts the goblins, but also the eagles, who arrive as the goblins and wolves set fire to the tree trunks. The eagles carry Thorin's company to their eyrie and once again Bilbo is nearly left behind, clinging desperately to Dori's legs.

In Tolkien's wider mythology the eagles are a manifestation of the Thought of Manwë, a force for good. Here they effect a vital rescue and will do so again in The Hobbit and LOTR. But for now we leave Bilbo and his companions in the eyrie, resting before they carry on towards the Lonely Mountain.

*source: Christopher Tolkien, HoME The Return of the Shadow, HarperCollins 1988
** source: Tom Shippey, Roots & Branches, Walking Tree Publishers 2007