A walking tour of the Far North of New Zealand introduces him to a range of characters, all of whom have an influence on his life. As Paul is involved with these people, he becomes aware of a dichotomy. He likens it to the conflict between Isaac and Ishmael, the two sons of Abraham, although for Paul, it is as if those two characters have taken up residence in his own personality.
Inside him, Isaac and Ishmael are struggling to dominate. The Isaac part of him pulls him towards a life of safety, of inherited wealth and respectability. Ishmael, who was banished to the desert by his father, offers a life of independence, of risk, of excitement and uncertainty. As the pull of the life of Ishmael gains strength, the longing Paul has for an academic career diminishes. But Ishmael is a rebel. When Paul learns the truth about an awful crime, he has to make the decision as to whether or not inform the authorities. Will the response be that of Isaac or Ishmael?