The mainpoint in chapter 79 of ‘The Currious Incedent of a Dog in the Night-Time ‘ by Marc Haddon is , that Christoper promises that he stopps his detectivework .
When Christophers father asks him where he was , he lies and says that he was outside . But he doesn’t tell that he did his detective work although he isn’t allowed to do that . His father gets very angry because he already knows that he does his detctive work because Mrs. Shears called him . Christopher tells Ed that he was the suspicion that Mr. Shears could have killed Wellington . His father gets very angry and explains Christopher that Mr. Shears is an evel man and that Mrs.Shears isn’t a friend anymore . Christopher had to promise that he stopps his detective work . So he does .