This sleuth's foibles provide much wit, without masking a keen mind that bodes ill for any wrongdoers.

He's the thinking sort of pianist, not the flashy kind - although a keen mind met pearly virtuosity in this concert's fine second half.

He was said to have had a keen mind and was quick at repartee in his polemical treatises.

Because of his keen mind and magical prowess (which he uses in secrecy), he becomes a feared inquisitor.

He possesses above-average intelligence and a keen mind for criminal strategy.