Joe comes home from school one day to discover that his apparently ordinary parents are actually spies! What's more, baddies are after them! They need to leave their home immediately and disguise themselves to avoid discovery. Joe is thrilled - until he discovers that he has to pretend to be a girl and start his new school as Josephine! Joe (now 'Josephine') is miserable when he starts his new school in a blonde wig, dress and tights. But soon he has a spy mission of his own. Using a host of unusual gadgets, Joe investigates some suspicious goings-on. But can he do so without revealing his true identity?