Please note that in order to properly annotate this novel, the novel's surprise ending will be revealed here. Snowman--who used to be called, Jimmy--is a rare survivor of a dreadful catastrophe that seems to have been both the product and the demise of modern science. He lives in a tree, clad in rags, hiding from relentless heat and hoarding his precarious cache of food and alcohol, while he tries to obliterate consciousness and avoid contact with a peculiar race of beings, the Crakers. Through a series of reminiscences as he makes his way back to where he once worked, Snowman's past slowly advances to meet his future.

The world heated up to be uninhabitable desert and genetic engineering created more problems (and species! [pigoons, rakunks, wolvogs]) than solutions. People became increasingly reliant on artificial environments--both internal and external--while their purveyors--drug and technology firms--held ever greater but unthinking power. The world was divided into two: the rich, safe controlled spaces and the dangerous chaotic realm of the poor. Then an epidemic wiped out most of the human race.

Two friends are central to the story: brilliant but inscrutable Crake whose nerdy gift for science had a role in engineering the 'pure' Crakers and the horrifying world that they occupy; and beautiful, seductive Oryx whose regard of knowing innocence heaps scorn upon messy human desire and emotion. They are the Yin and Yang of the "constructed" world. Only at the end, the reader learns that Oryx was murdered by Crake, who was slain by Snowman. It seems that his arduous journey was simply to destroy the history of the events that he had written and left behind.