It's supposed to be a treat for Kit, a winter holiday by the coast with her sister Libby and their mum. But when Libby vanishes into thin air, and no one else remembers her, Kit is faced with a new reality - one in which her sister never existed.
Then she meets Story, a local boy who remembers Libby perfectly.

Together they embark on a journey beyond their wildest imagination into a world steeped in ancient folklore. Can Kit and Story uncover the secret of the Twelve and rescue Libby before Time runs out?