The group stayed at Lake-town for a bit, and as autumn drew on, they made their way to the mountain. They had a map and key that told them of a secret back door so Smaug wouldn't know they were there.
Thorin, quick, the key! The light from the setting sun revealed a keyhole!
Bilbo was sent in to see what Smaug was up to. The dragon knew the hobbit was there, though he couldn't see Bilbo. Bilbo had to talk to the dragon to keep his life, so he got the dragon boasting.
Truly, you have no equal.
There, on his left breast, a bare patch!
No blade can pierce my mighty scales!
Unfortunately, Bilbo had let slip a comment about barrel-riding that told Smaug they'd been through Lake-town. He went to burn the city in his anger, and a thrush (an ancient, magical type of bird), told Bard, captain of the archers, about the dragon's soft spot.
Know your TRUE King Under the Mountain!!
Black arrow I have saved to the last, go now and speed well!
The dwarves had been in search for the Arkenstone, the heart of the mountian, when two armies, one of men and one of elves, came.
And what if we trade for what you search for?
You will have no part in the riches!
I gave them the Arkenstone, Thorin.
An army of dwarves came to help, but no sooner had they appeared than an army of goblins attacked. In the fierce battle, Bilbo was knocked out, but what he didn't see was Beorn and giant eagles coming to help defeat the goblins.
Bilbo woke up and was brought back just in time to be there when Thorin died, and get his forgiveness so the two could part as friends. Finally, his adventure was over.
Here you are home again, Mr. Baggins.
It's not proper for hobbits to go on adventures, but I'm quite glad I went on mine.