In the mythical world of Middle-earth, many thousands of years ago, the seven remaining members of the Fellowship of the Ring have been forced to separate after the fall of the wizard, Gandalf the Grey, into the pit at Khazad-dum. Hobbits Merry and Pippin have been captured by the enemy Urak-Hai, and the Elf Legolas, the Dwarf Gimli and their noble-born Human leader Aragorn have vowed to rescue them. Threatening Middle-earth is the mounting danger of the disembodied Sauron, who, from his dark tower of Barad-dur in the land of Mordor, maintains control through his puppet, the corrupted wizard Saruman of Isengard, who resides in his own tower, Orthanc. The task of destroying the master ring of power forged by the evil lord Sauron has fallen to the Hobbit Frodo and his loyal friend Sam. Frodo and Sam must cast the ring into the fires of Mordor’s Mount Doom before Sauron can use its power to take over the world. However, the Hobbits are lost in the hills and the ring’s dark magic is wearing Frodo down, physically and mentally. Increasingly, Frodo relies on Sam’s buoyant spirit, although Sam sometimes doubts if they should attempt the dangerous task. When they discover Gollum, a previous owner of the ring who lost it to Frodo’s uncle, skulking nearby, Frodo feels pity, knowing that prolonged contact with the ring deformed the creature’s mind and body. Despite Sam’s suspicions about Gollum, who insanely refers to the ring as “my precious,” Frodo asks Gollum to guide them to Mordor. Meanwhile, Pippin and Merry are being carried by Urak-Hais, the creatures bred for war from Goblins and the ancient war-mongering Orcs at Saruman's foundry, toward Isengard, where Saruman is forming a great army and communicates with Sauron via a seeing stone. Of strategic significance to Sauron’s plans is the kingdom of Rohan, where Saruman has already planted his spy, Grima Wormtongue, as King Theoden’s advisor. Saruman has cast a spell aging the king’s body and destroying his mind, so that the king shows no comprehension when his niece Eowyn tells him that Theodred, his only son and heir, lies dying after battling with Orcs. When Wormtongue denies that the Orcs are enemies and banishes Eowyn’s brother Eomer as a traitor, Eomer leaves with 2,000 men loyal to the king. In the countryside, they fight the many bands of Saruman’s amassing army who are wreaking havoc in the kingdom. One night Eomer’s men defeat the Uraks and Orcs holding Pippin and Merry. The next day Aragorn, Gimli and Legolas cross paths with the victorious Humans, and by inspecting the battle scene, conclude that the Hobbits escaped into the Fanghorn Forest of talking trees. Inside the forest, still pursued by a lone Orc intent on eating them, Pippin and Merry are saved by Treebeard, a creature belonging to the race of tree shepherds known as Ents. While searching for Pippin and Merry in the forest, Aragorn, Gimli and Legolas encounter a white wizard who they fear is Saruman. Instead, they learn that he is Gandalf, who, after falling through fire and water into darkness and timelessness, has been reborn as Gandalf the White. After explaining that he has been returned to Middle-earth to finish a task, Gandalf summons his horse Shadowfax and leads his companions to Rohan. Inside Theoden’s Golden Hall, Gandalf breaks the spell over Theoden, after which the king banishes Wormtongue. While grieving for his dead son, Theoden is alerted of Saruman’s approaching army by two children sent by a fallen village. The king, unwilling to engage in open warfare, orders his people to their fortress at Helm’s Deep, confident that the structure will protect them. Gandalf, who has misgivings about the fortress, convinces Aragorn to stay with the king, but before leaving, tells Aragorn to look to the east at dawn on the fifth day. To reach Mordor, Gollum takes Frodo and Sam through the Dead Marshes, where the weakened, mentally imbalanced Frodo falls in with the trapped souls. After being pulled out by Gollum, Frodo is nearly discovered by a ringwraith sent by Saruman. As they near Mordor’s gates, Sam and Frodo prepare to risk sneaking in behind an entering army. Gollum, afraid of losing his “precious” to Sauron, convinces them that he knows a secret way into Mordor. Sam still distrusts Gollum, but Frodo, who has realized that Gollum was once a being known as Smeagol who lived near his home, tells Sam that he wants to help him. Gollum, torn between loyalty to Frodo and his dark side that developed from exposure to the ring, battles with himself, but finally concludes that Frodo will take care of him. The next day, Sam and Frodo are captured by Humans from Gondor led by Faramir, the brother of former Fellowship member Boromir, who suspects they are spies. When Gollum is later found and threatened with death, Frodo, hoping to save him, admits that Gollum is his guide and lures the trusting creature to safety. After the guards capture the frightened Gollum, he thinks that Frodo betrayed him. Watching the disturbed Gollum argue with himself, Faramir learns about the ring Frodo bears and its power, and decides to take them back to Gondor. Although Sam suggests that Frodo escape by slipping on the ring, which will make him invisible, Frodo fears that Sauron, who can only sense him when he wears the ring, will find him. While preparing for the journey to Helm’s Deep, Aragorn becomes intrigued by the skilled swordsmanship of the noble Eowyn, but remains haunted by thoughts of Arwen, the Elf woman whom he loves. When Eowyn, who becomes increasingly attracted to Aragorn during the journey, asks him about the jewel he wears around his neck, he explains that it was given to him by Arwen, who he believes has left Middle-earth with her kinfolk for the "undying lands" in the West. Lapsing into a reverie, he recalls to himself how Arwen’s father Elrond told him that the time of the Elves in Middle-earth was over and that Arwen must leave with her people. Following Wormtongue's advice, Saruman sends Orcs riding vicious wolfbeasts called Wargs to attack Aragorn and his fellow travelers. Eowyn leads the women and children to Helm’s Deep on another path, while the men stay behind to fight. Although the king’s men are victorious, they suffer many casualties. Aragorn, who is dragged over a cliff into the churning waters of a river, is believed dead, but, unconscious and dreaming of Arwen, he floats to shore downriver and later reunites with the others at Helm’s Deep. In the Elf kingdom, all are preparing to leave, except Arwen, who considers abandoning immortality and family to remain behind for Aragorn’s return. By showing Arwen that by being immortal, she will eventually lose Aragorn, Elrond convinces her to join the Elves’ procession to the boats that will take them on their journey. Galadriel, the oldest of all the elves, is aware that Saruman has amassed an army of 10,000 to conquer Helm’s Deep and suggests to Elrond that they not abandon Middle-earth to Sauron’s dominion. At Helm’s Deep, shortly after Theoden, whose 300 men are mostly too young or too old for battle, confides to Aragorn that he feels alone and without alliances, an army of 200 Elf archers arrives to assist them. Meanwhile, Treebeard tells Pippin and Merry that the Ents have no interest in the affairs of men and wizards, but then, after finding more trees destroyed, calls a “gathering” of Ents to discuss whether to go to war. It is raining when Saruman’s forces reach the base of Helm’s Deep and the battle begins. Many of the enemy soldiers are killed by Elf arrows, but more scale the walls using ladders, and swords are drawn. At the same time, the Ents, who talk slowly, decide not to go to war. Treebeard offers to carry Merry and Pippin to the forest border nearest their Shire, but they ask instead to be taken toward Isengard where they hope to slip past the defenses, believing that the closer they are to danger, the farther they are from harm. Accepting their logic, Treebeard changes directions and upon seeing the destroyed trees near the Isengard border, calls out to the Ents, who gather from all over. Inside Helm’s Deep, after being forced to retreat to the fortress’ keep, Theoden feels defeated, until Aragorn suggests that they ride out to fight their enemy hand-to-hand. Defeat seems imminent until Aragorn recalls Gandalf’s words and looks to the east, where Gandalf and the 2,000 banished men of Rohan arrive to surprise the enemy from behind. As the defenders of Helm's Deep win the battle, angry Ents at Isengard destroy Saruman’s foundry and break down a dam, flooding the plains around the tower. In Gondor, Faramir is still planning to take the ring from Frodo, although Sam warns him that Boromir died trying. A ringwraith appears, to whom the weakened Frodo almost gives up the ring, but an arrow shot by Faramir sends it away. Although he is now safe, Frodo, still bewitched, turns on Sam and almost kills him. When his reason is restored, Frodo doubts that he has the strength to complete his mission. Inspired by the “great stories,” Sam says that all heroes doubt themselves, but they hold on, knowing that the good in the world is worth fighting for. Sam’s words are heeded by Faramir, who decides to release them. At Helm’s Deep, surveying the aftermath of battle, Gandalf predicts war for Middle-earth. Meanwhile, Frodo, Sam and Gollum have resumed their journey. Sam predicts that Frodo’s efforts will be put into songs and tales, and suggests that Frodo might become the most “famousist of hobbits.” Amused, Frodo says that “Samwise the Brave” is important to that story. Still feeling betrayed, Gollum mutters mysteriously to himself that “she” will make sure the Hobbits are dead, and then he can have his “precious” again. In a saccharine-sweet voice, Gollum calls out to the Hobbits to follow him and they continue on to Mordor and the fires of Mount Doom.