The Hobbit - Chapter 12 - Inside Information
The dark passage into the mountain stands open before the company. Thorin nominates Bilbo, the official burglar, to go inside to snoop. Bilbo enters, slips on his ring to make himself invisible, and proceeds down the long, dark passage into Smaug’s lair. There, he sees the magnificent, terrible dragon asleep on piles of treasure. Smaug is red and gold, with fiery breath, sharp claws, and a hide as strong as a diamond. Bilbo is horribly afraid, but he works up the nerve to take a single golden cup from one of the piles. He then rushes back up to the dwarves, who marvel over the cup. Bilbo’s theft does not go unnoticed by Smaug, who takes careful account of his treasure. When he awakens, he is enraged to discover that the cup is missing. He flies around the mountain breathing blasts of flame, and when he sees the company’s ponies at the foot of the mountain, he chases the ponies down and devours them. Meanwhile, the dwarves and Bilbo huddle inside the secret passage, terrified. After a while, Smaug returns to his den and falls asleep. The hobbit works up the nerve to return to the dragon’s lair, only to discover that the dragon has been feigning sleep. The terrible creature is wide awake, and Smaug is waiting for Bilbo.
Although he cannot see Bilbo because of the ring, Smaug smells Bilbo and greets him mockingly. Bilbo is smart, though, and answers Smaug only in riddles, which amuses the dragon enough to quell his anger for a while. Cleverly, the hobbit flatters Smaug into displaying his thick-skinned underbelly, revealing an open patch in Smaug’s scaly armor above his left breast.
Bilbo rushes back up the passage, just outrunning the dragon’s angry flames. The hobbit tells the dwarves all that he has learned while a thrush sits nearby and seems to listen. They then hear the roar of the dragon once more and shut the door to the passage just before an avalanche comes down upon it. They are trapped inside the mountain.