the brains behind (something)

the person who provides ideas and plans for an activity.

Someone very clever must be the brains behind such an organized group of thieves.

• hem and haw
• hem in
• hem in someone
• hem in something
• hen night
• hen party
• here and now
• here and there
• here go
• here goes
• here goes again
• here goes nothing
• Here's mud in your eye!
• here someone goes again
• here's to
• here's to someone
• here today, gone tomorrow
• here you go
• He wasn't born yesterday!
• He who pays the piper calls the tune.
• hidden agenda
• hide a multitude of sins
• hide head in the sand
• hide light under a bushel
• hide your head in the sand