To spoil, or not to spoil, that is the question:
Whether ‘tis nobler on the blog to make known
The most outrageous secrets of a book,
Or to write vaguely about an author’s ciphers,
And by saying naught preserve them?
Not to spoil, I think. Why should I rob you of the joy of discovery yourself?
My choice for the most surprising plot twists (yes, plural) occur in Chapters Four and Five of Tigana by Guy Gavriel Kay. So early in the book, and yet they change everything. Matters which had been presented as absolute fact are twisted on their head and given new meaning. One after the other these twists come, each disguised by the unexpectedness of the previous one, until eventually the reader is prepared to believe just about anything that happens.
“It was too much. Devin’s brain simply gave up trying to understand. Too many pieces of information were coming at him from too many different directions, contradicting each other ferociously. He felt dizzy, overwhelmed. He was in a room where only a little while ago he had stood among a number of men. Now four of them were dead, with a more brutal violence than he had ever thought to come upon. At the same time, the one man he’d known to be dead—the man whose mourning rites he had sung that very morning—was the only man of Astibar left alive in this lodge.
If he was of Astibar!
…Devin simply stopped trying to put it all together. He set himself to listen and look—to absorb as much as he could into the memory that had never failed him yet—and to let understanding come after, when he had time to think.” (108-109)
The reader’s experience is much the same as young Devin’s, but mixed with more air-punching at the sheer awesomeness of the proceedings.