I have never read or played this module.
From your review, it sounded like the first half is not an adventure at all but mere narration, by the GM, of events that occur to the PCs? Is that right?
Not quite. It has chances for the PCs to think they're interacting with the story. It's not "they get captured" it's "they get a chance to fight, but they'll be captured no matter what they do."