How does one write a "genius" character? I don't mean a scientific genius, or someone who is a prodigious talent in math or chess or something like that. I mean the following scenario (or an equivalent):
- Character G (for "genius") is a criminal mastermind who has just devised a brilliant scheme to make lots of money
- G is pursued by Inspector A (for "average"), an everyman detective who knows G is up to something and is itching to catch him in the act, even though he doesn't know what the plan is. In fact, A can't even imagine it because it takes special insight and/or knowledge to have thought of it.
It seems like brilliance of G's scheme (and of G himself) is necessarily limited by the ingenuity of the author. And if the author can't come up with a sufficiently ingenious plot for G to hatch, it's hard for the reader to believe that an ordinary person couldn't have thought of it ("Really? That's his plan? And Inspector A never saw it? How stupid is he?")