be the brains behind/of something | meaning of be the brains behind/of something in Longman Dictionary of Contemporary English | LDOCE

From Longman Dictionary of Contemporary Englishbe the brains behind/of somethingbe the brains behind/of somethingDEVELOPto be the person who thought of and developed a particular plan, system, or organization, especially a successful one  Danny’s definitely the brains of the project. → brainExamples from the Corpusbe the brains behind/of something• Bakewell senses that Rudd was the brains behind the fraud, but it was the brothers who were condemned to death.• Builtin computers are the brains behind them.• Maybe it was them who built the fences and he was the brains behind the organization.