PHRASE
(为了私利)保持缄默的密约
If there is a conspiracy of silence about something, people who know about it have agreed that they will not talk publicly about it, although it would probably be a good thing if people in general knew about it.
例句
Detectives have run into a conspiracy of silence in the tight-knit communities of the peninsula.
侦探们犯了难,半岛上各个群体抱成一团,达成了保持缄默的密约。