东窗事发 The matter in the east window is revealed
Explanation
东窗事发指的是秘密或阴谋被揭露，比喻秘密或阴谋被发现，通常是指事情败露，真相大白。
Dongchuang shifa refers to the disclosure of a secret or conspiracy, which means that a secret or conspiracy has been discovered, usually referring to the disclosure of something and the revelation of the truth.
Origin Story
相传，秦桧在南宋时，为了维护自己的利益，残害忠良，并陷害了抗金英雄岳飞。为了让岳飞远离朝堂，秦桧与妻子王氏在东窗下秘密策划，最终以莫须有的罪名将岳飞杀害。后来，秦桧父子因病相继去世，王氏请僧人做法事超度他们，僧人说：“太师叫我转告，东窗事发了。”这个故事流传至今，成为民间广为流传的典故，用来比喻秘密或阴谋被揭露。
It is said that Qin Hui, during the Southern Song Dynasty, in order to protect his own interests, persecuted loyal officials and framed Yue Fei, a hero who resisted the Jin. In order to keep Yue Fei away from the court, Qin Hui and his wife Wang secretly plotted in the east window, and finally killed Yue Fei on the pretext of a non-existent crime. Later, Qin Hui and his sons died of illness one after another, Wang asked a monk to perform a ceremony for them, the monk said: “The Prime Minister asked me to tell you that the matter in the east window has been revealed.” This story has been passed down to this day and has become a well-known proverb among the people, used to refer to the disclosure of a secret or conspiracy.
Usage
这个成语常用在揭露秘密、阴谋、丑闻等场合，表示事情真相大白，无法隐瞒。
This idiom is often used in situations where secrets, conspiracies, scandals, etc. are revealed, to indicate that the truth is coming to light and cannot be concealed.
Examples
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他的秘密终于东窗事发，被大家知道了。
tā de mì mì zhōng yú dōng chuāng shì fā, bèi dà jiā zhī dào le.
His secret was finally exposed.
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这个阴谋很快就被揭穿，东窗事发了！
zhè ge yīn móu hěn kuài jiù bèi jiē chuān, dōng chuāng shì fā le!
The conspiracy was soon exposed!