The Two Towers opens with the disintegration of the Fellowship, as Merry and Pippin are taken captive by Orcs after the death of Boromir in battle. The Orcs, having heard a prophecy that a Hobbit will bear a Ring that gives universal power to its owner, wrongly think that Merry and Pippin are the Ring-bearers.
Meanwhile, Merry and Pippin are being conveyed back to Orc headquarters when Orcs from another tribe, the Uruk-hai, kidnap them in pursuit of the Ring they believe the hobbits to be carrying. Pippin and Merry escape the Orcs and travel through the forest near the Entwash River, where an Ent (a giant treelike creature) named Fangorn befriends them. Fangorn offers the hobbits nourishment and conveys them to an Ent assembly. There, the Ents resolve to go to war against the Orcs of Isengard (creatures controlled by the corrupted wizard Saruman), who have been cruel to them.
Meanwhile, Saruman haunts Aragorn and his group as they travel the forest. Gandalf then appears to them, reborn after his earlier death in The Fellowship of the Ring as Gandalf the White, also known as the White Rider. Gandalf guides Aragorn’s group to Edoras, the Golden Hall of King Théoden. There, Gandalf exposes Théoden’s counselor, Wormtongue, as a spy for the evil Saruman. Gandalf also facilitates a reunion between Théoden and Éomer.
The group then proceeds to confront Saruman at Isengard, where they are surprised to find Merry and Pippin at the gates of Saruman’s headquarters. The hobbits tell Gandalf that the Ents wish to meet with him, to offer their aid in the struggle against Saruman. The group finds Wormtongue in Saruman’s tower, Orthanc. Wormtongue tries to kill Gandalf by throwing an object down on him from a window. That object is a palantír, a magic seeing-stone that transmits images. Pippin looks into the palantír, which allows the Dark Lord Sauron to discover where Pippin is and pursue him.
Can’t tell you any more than that. Watch the movie!!