Any specific one you would recommend?

Most of the ones below seem somewhat too basic for me.

http://www.amazon.com/Paul-J.-Nahin/e/B001HCS1XI/

I read An Imaginary Tale and liked it. That being said, I have more enthusiasm than ability when it comes to maths. You might very well be beyond these books.

In university libraries you can sort of pick out narrative/casual books in the math section by working off of the form factor. If you pull out books with a novel-like size and shape and read the backs you might find ones that are the right mix for you.

One last clue is that publishing houses like Springer will put out series of more narrative or casual works from time to time. Best of luck!

I think I started reading one of them, but didn't really connect with his writing style. I should probably give it another go though, I might just have been in a bad mood.