One night a great big, white polar comes to stay with Tilly. The bear's got black hooked claws and huge yellow teeth; but his white furry coat is warm and soft and Tilly decides he's the cuddliest thing in the whole world. Tilly soon finds out that a big bear can cause big problems - he takes a LOT of looking after! But when she describes the bear's latest antics to her parents they think he's a figment of her imagination - but is he?