Thunder Rules! — Marie Joyce

When two ordinary children find a strange metal object buried in their garden, they become suddenly entangled in a fantastical world of magic. Disappearing children, vegetarian sausages, Goblins, dragons and an amazingly magical man lead them into a spectacular adventure... Thunder the evil fairy is destroying the planet! The children and their magical friend must race against time to rescue the fairy princess and save the world before he succeeds.