Horrid Henry has had enough of his tale-tale of a brother Perfect Peter getting him into trouble. He decides it's about time his took revenge... When Henry accidentally paints Peter blue, he’s taking to his room by his Mother for his mishap and for a very long time and all his stuff is confiscated. But he has the last laugh when he finds a way to get Peter into trouble, and not only Peter but the Best Boys Club too – revenge is sweet, especially when it’s coloured blue.