The Clerk's Tale and the expectation of astonishment
Penelope Fitzgerald mentions this as one of the stories that developed her love of plots with a twist at the end. But it appeared on the 1970 A-level exam with this question: 'Whatever its other merits, The Clerk's Tale does not achieve its effects primarily through surprise.' So is it a plot with a twist or not?
Here's the story. Walter the Marquis marries Griselda a village girl. He decides to test her wifeliness and has her children taken away at birth. She thinks they have gone to die. Another Marquis, however, raises them in secret. Years later, Walter tests Griselda again: he sends her home and tells her he is marrying a younger woman. Griselda dutifully goes home but comes back to help with the wedding preparations. The big surprise is that the children are coming back. Instead of marrying one of them, Walter presents the young woman and the young man to Griselda as her returned children.
Obviously, in many ways, the ending is not a surprise. We know the children were secretly raised by the other Marquis. The genres of religious faith (Griselda is Job) or testing the wife involve this sort of thing. Maybe we would be surprised by the plot if we weren't familiar with the genre, but that's not a very good answer.
And I don't think it's true. Anyone reading this story must get the lurking feeling that Walter is not really killing the children. He calls it a test. That means we pretty much know what's going to happen. The wedding doesn't fool the reader. That tells us what to expect. Much like will-they-won't-they plots we might not feel certain of the ending, but we know approximately what it's going to be.
The surprise comes from the expectation of astonishment. Just because we can figure out the sort of thing Walter is up to, doesn't make it less shocking. If I could predict the future (in a credible way) and told you someone would fall off a building, you would still be horrified when you saw it happen.
Every time Walter tests Grisleda, we feel the expectation of astonishment building up. It's a plot mechanism like suspense, because we know what to expect, but what we expect is terrible. Dramatic irony heightens our sense of astonishment because it takes away the surprise.
Of course, like The Winter's Tale, another story that uses the expectation of astonishment as its main plot driver, there is a happy ending. How could someone who loves his wife and doesn't want to leave her do something like this, and how could they end up with a happy ending.
The answer is that this is not a realistic story, it's an allegory, a parable, to teach religious forbearance. But at the purely plot level, to answer that A-level question, The Clerk's Tale works through the expectation of astonishment.