距离孤山越来越近，矮人远征军的道路却变得异常艰险。他们躲过了苍白半兽人的不懈追杀，在幽暗密林前和甘道夫（伊恩·麦凯伦IanMcKellen饰）兵分两路，后者前往多尔哥多探寻索伦的动向，而霍比特人比尔博·巴金斯（马丁·弗里曼MartinJohnC.Freeman饰）和矮人们先是遭到巨大蜘蛛的袭击，随后又被精灵王子莱戈拉斯（奥兰多·布鲁姆OrlandoBloom饰）及其木精灵同伴捕获。比尔博急中生智，利用魔戒救出伙伴，继而引发了木精灵、半兽人和矮人远征军之间精彩纷呈的三方会战。借助巴德（卢克·伊万斯LukeEvans饰）的帮助，疲惫的矮人们暂时落脚长湖镇。近在咫尺的孤山城堡，沉睡在财宝中的巨龙即将醒来……
　　本片根据J.R.R·托尔金的同名原著改编。

　　Revolt is on the horizon in the ancient city of Lloris, ruled with an iron fist by the merciless Sheriff (Lord of the Rings’ Billy Boyd) and The Brute (The Hobbits’ Ryan Gage). Believing their mystical powers could help free the oppressed citizens from tyranny, a young human seeks out the aid of the reclusive elves and their legendary Warlord.
　　
　　However, with both sides harbouring secrets, and hiding their true motives, this tentative alliance between the humans and elves may bring about the downfall of them all.