It's supposed to be a treat for Kit, a winter holiday by the coast with her sister Libby and their mum. But as the solstice moon rises high in the sky, Kit and Libby are drawn to a mysterious white tower, only to face disaster when Libby vanishes. The world has rewritten itself, leaving Kit to navigate a reality where her sister has never existed. Even their mum doesn't remember her.

But then Kit meets Story, a local boy who remembers Libby perfectly. He teams up with Kit and together they embark on a perilous journey fraught with dangers beyond their wildest imagination, crossing a world steeped in ancient folklore. Can Kit and Story uncover the secret of the Twelve and rescue Libby before Time itself vanishes?