I've said it in every other post about these books so far, but I will say it again: you should read The Lord of the Rings. If you haven't read them, then a) I'm very sorry for the sad life you have heretofore lived, and b) you should read them immediately. If you have read them, then you should reread them. These are the kinds of books that spoil you for everything else that isn't nearly half as good as they are.
At the end of The Two Towers, if you're not familiar with the plot already, you'd probably believe that this story is not going to end well. Of course, the biggest spoiler of this book is its own title, which Tolkien did not pick. His original choice for the title of the third part of The Lord of the Rings was The War of the Ring, but he was persuaded to change it to the more positive, and arguably more descriptive, The Return of the King. Knowing this history, I'm not entirely certain which title I prefer. However, I am entirely certain that I enjoyed this part of the story just as much as the others.