twist

A plot twist is a literary technique that introduces a radical change in the direction or expected outcome of the plot in a work of fiction. When it happens near the end of a story, it is known as a twist ending or surprise ending. It may change the audience's perception of the preceding events, or introduce a new conflict that places it in a different context. A plot twist may be foreshadowed, to prepare the audience to accept it, but it usually comes with some element of surprise. There are various methods used to execute a plot twist, such as withholding information from the audience, or misleading them with ambiguous or false information. Not every plot has a twist, but some have multiple lesser ones, and some are defined by a single major twist.
Since the effectiveness of a plot twist usually relies on the audience's not having expected it, revealing a plot twist to readers or viewers in advance is commonly regarded as a spoiler. Even revealing the fact that a work contains plot twists – especially at the ending – can also be controversial, as it changes the audience's expectations. However, at least one study suggests that this does not affect the enjoyment of a work.
Many television series, especially in crime fiction, use plot twists as a theme in every episode and some base their whole premise on the twist; for example, The Twilight Zone and Tales of the Unexpected.

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