Focusing on a British police officer in an unnamed West African colony, this novel attempts to show, along with the socially restricted lives of colonists in Africa, the effects of sin on a devout catholic. After sending his unhappy wife to South Africa at her request the officer begins an affair with a young woman, a survivor of a shipwreck and now widowed but is unable to end the relationship when his wife returns even though he feels he is committing a mortal sin.