Maggie's father is 'Mr Safety'. He knows the woods of Duchess Creek in Northern Canada like the back of his hand, and he has taught his daughter how to survive, how to find and make a shelter in all weathers, in any conditions.
Along with her sister, Jenny, and their mother Irene, they are safe from the outside world.
But when an accident at work goes fatally wrong, Irene struggles to look after her daughters alone.
Wild, imaginative and unpredictable, she billets the two girls with a family, promising to return once the summer is over and she has earned more money.
But the summer turns to winter, which rolls round again and again.
When the letters stop, the two sisters realise that they can rely on no one but themselves - but what kind of shelter can two young girls make for themselves?