The main issue raised is how we can square human altruism with the Darwinian notion that individuals will always act in their own self-interest. The story is set in Africa in 1913 as two scientific parties set out to observe chimpanzees. The narrator is basically on his own, but meets up with a British Expedition being led by Lady Jane Sevile, with whom he proceeds, rather spontaneously and implausibly, to have a torrid affair.