Josh is woken by a trumpet-playing Brian and is offered tiddlywinks for breakfast. His sisters may be technically human but they still can't behave like normal people. Why can't his family just be different in every way? A bump on the head makes Josh's wish come true, throwing him into a world of complete opposites. Lucy is stupid, Mel cares about what she looks likes and fancies Frankie, Sophie doesn't even try to be a good mum, Pete is short and fancies Mel and Frankie is tall doesn't like Mel but all of the other girls fancy him. Wendy is his girlfriend and like Lucy, is thick, but more clumsier than Lucy. And Mrs. Hardman is the art teacher and fancies Brian. This leaves a whole world of confusion and he wishes that he could have been fostered by someone else.

Meanwhile, the opposite Lucy and Wendy, are trying to write a story to win a day with Chubby the Bear but don't write much. And when Sophie enters too, Josh has to stop her from entering.