At first, John Egan seems a normal enough twelve year-old, but as the novel develops, we are enabled to explore a rare kind of psycholgical abnormality, although it is not until near the end that this becomes really apparent. The narrative device of using the present simple tense is used by the author to take us inside the boy's mind as he observes the world around him, and although there is plenty of action, this is what the the novel is really concerned with.
John becomes obsessed with the truth or falsehood of what others are telling him, and comes to believe that he has a unique gift for detecting lies. This obsession has tragic consequences for his parents' marriage, and leads to an enthralling climax.
I enjoyed the atmosphere of Dublin and the Irish countyside created by Hyland and much of the characterization is convincing, but some of the realism is not for the over-sensitive.