I disagree with The_Colonel. Part 3 has a different setting from the rest of the book, but is still part of the overall story. It is a logical extrapolation of

I disagree with The_Colonel. Part 3 has a different setting from the rest of the book, but is still part of the overall story. It is a logical extrapolation of the first two parts, and specifically follows up on a plot twist that appears at the end of part 2.