I've been meaning to read about Alfred Russel Wallace for a long time. When a kind soul bought me this book from my wish list, I had no further excuse.
For those of you who don't already know, Wallace is the chap who came up with the idea of evolution by means of Natural Selection independently of Darwin. At the time, Wallace was cooped-up in a hut in deepest Malaysia. He immediately wrote up his idea and posted it to Darwin, who nearly had a fit: Darwin had been researching his theory for twenty years, but had never published, fearing the backlash. Eventually, Darwin's friends convinced him to publish a joint paper with Wallace's (without Wallace's knowledge—he was too far away to consult). The paper went relatively unnoticed, but Darwin's shock at almost being scooped encouraged him to get his act together and write Origin of Species.
Wallace was never of the scientific calibre of Darwin, but he was undoubtedly a great explorer and naturalist. This book goes a long way to restoring Wallace's reputation, without going over the top (as certain conspiracy theorists have) by claiming that Darwin stole Wallace's ideas.