Do you mean ' the twist of the tale'?
A twist is an unpredictable event or a quirk in the smooth flow of a 'story', like in:
a twist of fate (when something unexpected happens that changes your life, or fate).
Likewise, a twist of a tale can be a sudden sharp turning point in the tale that creates suspense and takes the reader by surprise. It does not bring the story to an end, only changes its course of action in a completely different direction.
"Suddenly, there was a knock on the door. When the door opened, a stranger came in and wanted to talk to dad..."
- sounds like bad news to me...