Introduction: The Return Of The King
Each of the books of "The Lord of the Rings" represents a different phase of the story. Fellowship of the Ring is primarily exposition and a gradual broadening of the scope from the Shire to the larger, more diverse world of Middle-Earth. The Two Towers lays out the beginnings of the larger Quest and the War of the Ring, as told in two main parts. The events, separated by the physical barrier of the River Anduin, leads to both an increase in the action and a development of multiple plot layers that wind themselves towards a common resolution. Return of the King is that resolution, or climax, of the realization of the destruction of the Ring and the ultimate defeat of Sauron. And yet a full two thirds of Book VI is dedicated to the resolution of many loose ends. Ultimately, the scope once again narrows back to where it began, with the Shire.
As Tolkien layed out the two story lines in separate parts of the The Two Towers, he does not end them at similar chronological points. In fact, Book IV advances Frodo and Sam's story a full eight days beyond where we last left off in the West, with Gandalf and Pippin galloping swiftly towards Minas Tirith. Similarly, Book V will advance past Frodo and Sam by ten days to March 25th, leaving an uncertainty to the first time reader about the Quest to Mount Doom. The effect will be to heighten the suspense. By the time Aragorn and the Army of the West reaches the Black Gate, the reader experiences the same doubt and despair that they do over the fate of Frodo and the Ring.
Finally, by Chapter Four of Book VI all of the characters are chronologically "in sync". The separate plot strands will weave themselves back together to reunite the Fellowship (sans Boromir) that set out together from Rivendell. The excitement of finishing the story with Return of the King is tempered by the realization that, like Frodo, we will soon be leaving Middle-Earth.
But now, let's begin with Chapter One: Minas Tirith.