In the final book of the series, Isabel discovers the greatest secret of the ancient Isle of Portland. `You're a witchy family. Your mum's got red hair and your sister's a pumpkin!' remarks Noah, Isabel's friend. But the local elves think Isabel isn't a proper witch, even when she encounters a ghostly highwayman and cavalier, a headless horseman, magical unicorn and the keeper of the old Vindelis Lighthouse, a boy lost in time. Her interfering little sister Suzie is keen to find the Island Giant, but Isabel is worried. What will he think of today's Portland and of Isabel herself, the reluctant island witch?