Gandalf and Aragorn lead the World of Men against Sauron's army to draw his gaze from Frodo and Sam as they approach Mount Doom with the One Ring.

While Frodo and Sam edge closer to Mordor with the help of the shifty Gollum, the divided fellowship makes a stand against Sauron's new ally, Saruman, and his hordes of Isengard.

In Narnia (world), almost 1300 years after the Pevensie siblings left. Caspian X, a Telmarine prince, is awoken by his mentor Doctor Cornelius, who informs him that his aunt has just given birth to a son and that his life is now in grave danger. Cornelius gives him Susan Pevensie ancient magical horn and instructs him to use it if he is in dire need of help. Knowing that his Uncle Miraz would kill him in order to be king, Caspian flees. Chased by several Telmarine soldiers, Caspian falls off his horse and encounters two Narnian dwarfs and a talking badger in the woods. One of the dwarfs, Trumpkin, is captured by the soldiers after sacrificing himself to save Caspian, while the other dwarf, Nikabrik, and the badger Trufflehunter, save Caspian. Not knowing that they are trying to save him, Caspian blows the magical horn, trying to summon help.