The Dwarves of Erebor have reclaimed the vast wealth of their homeland, but now must face the consequences of having unleashed the terrifying Dragon, Smaug, upon the defenseless men, women and children of Lake-town. As he succumbs to dragon-sickness, the King Under the Mountain, Thorin Oakenshield, sacrifices friendship and honor in his search for the legendary Arkenstone. Unable to help Thorin see reason, Bilbo is driven to make a desperate and dangerous choice, not knowing that even greater perils lie ahead. An ancient enemy has returned to Middle-earth. Sauron, the Dark Lord, has sent forth legions of Orcs in a stealth attack upon the Lonely Mountain. As darkness converges on their escalating conflict, the races of Dwarves, Elves and Men must decide—unite or be destroyed. Bilbo finds himself fighting for his life and the lives of his friends as five great armies go to war.