Final answer:
Dramatic irony is the plot device that lets the audience know something before the leading characters.
Step-by-step explanation:
The plot device that lets the audience know something before the leading characters is dramatic irony. Dramatic irony occurs when the audience has information that the characters do not, creating tension and anticipation. This can happen in various forms, such as when the audience knows that a character is walking into a dangerous situation while the character remains oblivious.
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