The irony in this scene is that the audience knows that the boy heard what his mother was saying to Ross about Macduff however, she tells her son that he is dead when he knows his father is not.For example Lady Macduff says, “All is the fear and nothing is the love,/ As little is the wisdom, where the flight/ So runs against all reason” (4.2.12-14). Lady Macduff tells her son that his father is dead because she believes that he has abandoned his family and left them to pick up the pieces and that is the same to her as him being dead.