On 24th November 1859, Charles Darwin's On the Origin of Species was first published, selling out almost immediately. Describing the now well known theory that humans evolved through a process called natural selection, it became an instant classic and cemented Darwin as one of the greatest biologists of all time. However, he couldn't have done it without the support, encouragement and advice from those who believed in him. None more so than Joseph Hooker, his friend, confidant and fellow collector, who supported and helped Darwin when he didn't dare ask anyone else. Hooker, too, had his own adventures and made his own discoveries many of which not only aided Darwin, but went on to change what the world knew about plants. Becoming head of Royal Botanic Gardens, Kew, he came to be one the world's most influential botanists. Across many years, countless adventures and numerous letters, this captivating and wonderfully illustrated book tells the story of one of greatest friendships to happen to science.