I'll be starting from the middle of the story, at the part where the party meets Beorn, a gigantic man/bear (and appearantly also a wizard), who has a strong dislike of Goblins, Wargs and everything that is on the evil-side in this story. Luckily Gandalf felt like sticking around this while, because he seemed to know how Beorn would react to big groups of people. They don't get into trouble there for a change, and then move on with the ponies which Beorn so royally provided for their temporarily use. Those ponies, by the way, probably would have tasted very good to Smaug, seeing as he likes ponies. The next part of the journey is quite grim, especially knowing Gandalf had something better to do, at the edge of the most dangerous possible forest they were to encounter, and had to leave. Oh, and they would have to walk trough the forest and send the ponies back. In the forest the thirteen Dwarfs and one little Hobbit happily ignored Gandalfs'warning to not stray from the pad, because they thought they saw something to eat. To make the long story short, they kept falling into the same trap for about 3 times (a donkey only hits the same stone...). And everyone but Bilbo gets trapped by the ancestors of the Harry Potter spiders. Bilbo proves to be useful, and after they're freed, they go on and get imprisoned by Wood-elves just a little bit later, again, everyone but Bilbo. Seeing as the book doesn't stop there, you already know they will escape, because the elves wanted to let them be imprisoned for a while, so you know they wouldn't just let them go. Bilbo frees the Dwarfs, and they escape using empty barrels. The Dwarves and Bilbo literally go with the flow to the village of the Lake-men. Even more luck, this village had long-awaited the Dwarfs(nothing about Bilbo in the prophecy) and supply them with ponies, food and whatever necessary for their journey towards the treasure. Oh, and the big enormous -and probably not feeling like being disturbed- Dragon right on top of it. After that, their journey continues, first by water, with escorts, later over the barren grounds of what once was Dale. They go onwards to an old door, which was once used, ironically, to abandon the treasure, involuntarily, that was. Well, after leaving Bombur and Bofur with the ponies and packages, they find the door and try to open it, which they can't (at first). So they got everything necessary from the ground, happy to have found the path, of course. Then they succeed in opening the door, and Bilbo is the first victim to be send down the little passage. At the and of the path he finds Smaug sleeping, then steals the first thing he sees, and rushes back to the Dwarfs. Smaug wakes up, finds out, and feels like having a Dwarf for breakfast. Now all Dwarfs went in the tunnel. Well before that, Bilbo had went down the road again, and Smaug was awake. They had there nice little chat, and then Smaug goes to the outside of the mountain, and the Dwarfs go in. They close the door, something the Dwarfs especially didn't like. Smaug goes the village, leaving the mountain for a while. The Dwarfs have no choice but to go down the tunnel, to Smaugs nest (their treasure). Meanwhile, Smaug tries to burn down the village. A once young man (now old), heir of Dale, kills the dragon with one shot (of an arrow of course). Smaug is dead, and the villagers think the Dwarfs are in the same condition, that's also why they don't hate them, even though it is the Dwarfs' fault Smaug woke from his slumber and attacked. They team up with the Woodelves and head for the treasure, which the Dwarfs have already confiscated. When they meet each other (-again), the Dwarfs are not willing to give even an ounce of the treasure away, not even for killing Smaug, nor to repay them for their kindness. Bilbo silently doesn't agree, he sneaks away that night, and goes straight to the camps of the men and elves. He explains the plan and gives them the Arkenstone, which Thorin had been looking for ever since they arrived in the cave, no, where Thorin was looking for since the start of the journey. When his plan comes into play, the Dwarfs kick him out, despicing him for what he has done. Thorin trades the Arkenstone for the 14 percent of the treasure that used to be promised to Bilbo. Bilbo doesn't care; he just wants to return to his nice little Hobbithole. Suddenly Orks appear, Bilbo gets knocked out (again), wearing the ring. Just before he gets knocked out, the eagles appear, and soon the battle ends, a lot of men, elves and Dwarfs are killed, also Fili and Kili. Thorin is heavily injured, departs the world after he made up with Bilbo, and he gets burried with the Arkenstone. On his way home he picks up the treasure that once belonged to the trolls, which buried by the Dwarfs (They will probably be very angry when they find out, seeing that they are very stingy in matters concerning treasure).
Bilbo was finally almost back to his hole, when he finds out that everybody thinks he's dead, and they are selling his stuff. The end -He kicks them out