Zizou Corder is Louisa Young and Isabel Adomakoh Young, whose names are too long to fit on the front of a book. Louisa is a grown-up and has written five grown-up books. Isabel is a kid and has written mostly schoolwork. The original Zizou is Isabel's lizard, only he spells it Zizu. This is their third novel – the last in a trilogy that has sold more than 200,000 copies so far in the UK alone. They all live in London. Only one goes to school.