black curtain
Literal meaning: a black curtain used in theater or as a backdrop. Less common in everyday speech than the figurative sense.
The black curtain on the stage rose quietly.
wirepuller; mastermind; éminence grise
Figurative use: a person who controls events from behind the scenes, often in politics, business, or crime. Carries a slightly negative or conspiratorial tone.
The mastermind behind the incident has not been caught yet.
He is known as a power broker in political circles.
The mastermind behind the incident has not yet been caught.
He became the mastermind controlling the company from behind the scenes.
The reporter tried to expose the mastermind behind the incident.