Imagine a dark, stormy night in the South Atlantic at the end of December 1832. Aboard the Royal Navy survey vessel HMS Beagle a young naturalist, racked with seasickness, staggers on deck. A sudden wave makes the ship heel violently, and he is washed over the side. The lookout calls "Man overboard!" but it is too dark to see anything in the churning sea, and the storm is too fierce for the officer on watch to risk turning the ship about. Charles Darwin is gone, and Captain Fitzroy will have to face the task of writing to his family in England to break the news. He will certainly tell them that in addition to their personal tragedy, the scientific community has lost a promising young naturalist who might have achieved great things. But he has no idea that Darwin's greatest achievement would have been to write one of the most controversial books of the century, a book that Fitzroy himself would have denounced in public: On the Origin of Species.