I usually don't review the non-fiction I read, but this is too extraordinary to pass up. S. Ramanujan was an Indian autodidact and mathematical genius who came to England in 1913 to work with the Cambridge mathematician G.H. Hardy. Ramanujan's story is astounding, and the partnership between the two is a friendship complicated by the differences in their age, religion, and culture.
Kanigel's book is beautifully written. He manages to work in some of the math in a way that sparks the curiosity of a non-mathematical reader, and the book is crammed with enchanting 'you-are-there' detail as it moves from Madras to Cambridge.
If you don't have time for the book, I hope you'll see the 2015 movie staring Dev Patel and Jeremy Irons because Ramanujan was a phenomenal genius. You can view the trailer on YouTube.