The lives of mathematician Kurt Gödel and computer pioneer Alan Turing are the subject of a slightly fictionalised biography, reviewed here.
Lots of things I didn't know about them -- have a biography of Turing sitting on the shelf unread and managed only a third of "Gödel Escher Bach" back in the 80s when it was all the rage.
Most shockingly, I didn't know how Turing killed himself: as he was obsessed with Disney's Snow White, he bought a red apple every day. The last one he injected with cyanide. What a story.
PS the book is:
A Madman Dreams of Turing Machines
by Janna Levin
230pp, Weidenfeld & Nicholson, £14.99