to be in control of an organization, often secretly.

I'd really like to know who's pulling the strings in that organization, because it's not the elected committee.

• at all hours of the night
• a tall story
• a tall tale
• at a loss
• at a loss for words
• at a low ebb
• at a moment's notice
• a tangled web
• at any cost
• at any price
• at any rate
• at a pinch
• at a premium
• at a price
• at a push
• at a rate of knots
• at a snail's pace
• at a stretch
• at a time
• at beck and call
• at best
• at convenience
• at cross purposes
• at cross-purposes
• at death's door