This book begins in one small, dark room with two opposing theories about knowledge. It then takes the reader on an epic journey through the political, social, and academic landscape of the twentieth century, before returning back to the dark room with the two personalities behind the theories - which is always going to be more fun.
It's sweep is misleadingly vast. Popper and Wittgenstein are at the same time seen as heavy-weights in a self-conscious world, and pawns in the greater game going on around them. That so much history, biography and philosophical theory can be contained within so few pages is incredible. The lives of Popper and Wittgenstein could not fail to produce an epic tale, but so much credit must go to the authors for understanding that no piece of information is too small in a detective story, and that it doesn't matter from which quarter the information comes, be it philosophic tomes, old letters, reconstructed memories, or even forgotten memos passed between low-ranking Nazi officers.
The book defies categorisation. It is far and away the most original premise of the year. Informative, vast and brilliant.