often said after a turning point in the plot
It usually refers to things
becoming overly complex
or mysterious. Today this term is often Played for Laughs
. Coined in the 17th century, it originally described the plot of a play that was overly intricate, and by the late 1800s it was used for increasingly complex mysteries in detective stories
The phrase is sometimes parodied as "The plot sickens". You may also hear "the plot thins" - usually uttered after a major Anti-Climax
- Hawaii Five-O (1968) pilot episode.
Wo Fat: As we clever Chinese say, "The plot thickens..."
- Knight Rider episode "Mouth of the Snake"
Michael Knight: So, the plot thickens. I bet this guy David Dalton is not down in Mexico looking for the world's biggest burrito.
- The League of Gentlemen
Pauline: It's about Mickey. He's getting married.
Ross: Oh-ho. The plot thickens.
- Roald Dahl used this to customary darkly comic effect in his retelling of Cinderella
Ah ha, you see, the plot grows thicker,
And Cindy's luck starts looking sicker.
- Justice League - When Luthor's soon-to-be Injustice Gang sees who's gathered them, the Shade quips, "Lex Luthor? The plot thins."