Immediately after the events of The Desolation of Smaug, Bilbo and the dwarves try to defend Erebor's mountain of treasure from others who claim it: the men of the ruined Laketown and the elves of Mirkwood. Meanwhile an army of Orcs led by Azog the Defiler is marching on Erebor, fueled by the rise of the dark lord Sauron. Dwarves, elves and men must unite, and the hope for Middle-Earth falls into Bilbo's hands.

As armies mass for a final battle that will decide the fate of the world--and powerful, ancient forces of Light and Dark compete to determine the outcome--one member of the Fellowship of the Ring is revealed as the noble heir to the throne of the Kings of Men. Yet, the sole hope for triumph over evil lies with a brave hobbit, Frodo, who, accompanied by his loyal friend Sam and the hideous, wretched Gollum, ventures deep into the very dark heart of Mordor on his seemingly impossible quest to destroy the Ring of Power.​