master plan

A plan that you've schemed out and know is gonna work. Perfect for explaining to someone through song

Grover Fischoder: Would you like to hear my master plan?
(silence)
Grover Fischoder: Okay, could you answer faster? 'Cause I asked you: Would you like to hear my master plan?
Louise: Uh, yes?
Grover Fischoder: Okay, that's more like it, I'm so glad that you asked!