Thirteen-year-old Tess is a Switcher, able to change into any animal at will. No one knows her secret, or so she thinks. But one day a strange, scruffy boy follows her home from her Dublin bus stop. The boy’s name is Kevin, and he’s a Switcher too. Kevin convinces Tess that their powers are needed for something important: stopping the snowstorms rapidly advancing from the Arctic. Tess and Kevin will have to stretch their abilities to the very limit to try and save the world from frozen destruction.