While her milliner mother Rosamund is abroad in Paris, twelve-year-old Vinnie Fyfe is left behind in Brighton. She finds comfort in her eccentric Aunt Bets, her new friend Temitayo, and the Brighton Aquarium - where the arrival of a giant octopus will change her life forever. At first terrified, then fascinated, Vinnie begins to produce drawings of the incredible creature, and is sure that a bond is developing between them. But meanwhile there is a dark and dangerous mystery afoot - involving Rosamund's real reasons for disappearing so suddenly, and the ominous behaviour of her former employee Mr Jedders . . .