If you're looking for a well-written, captivating fantasy book, I know just the book(s) for you. It's a series of fantasy books called a song of ice and fire, by George R. R. Martin, and it's the best fantasy I've ever read.
The first book in the series is called A Game of Thrones, so that is where you should start. The books are very well-written and the story is simply amazing. It has some excellent plot twists, and you're never sure what is going to happen next. I highly recommend those books.
Be aware, though, that the series isn't finished. Martin just finished the 4th book, called A Feast For Crows, and three more are planned, although it could easily be more than that (originally, only six books were planned, but the fourth book got so massive that he had to split it in two).
Anyway, if it's good fantasy, you're looking for, this is definitely it. It's the best there is.
Edit:
Spoiler-free review