In the seaside village of Watchcombe, young Kate is determined to make the most of her last week of summer holiday. But when she discovers a mysterious painting entitled 'The Lord of Winter' in a charity shop, it leads her on an adventure she never could have planned. Kate soon realises the old seascape, painted long ago by an eccentric local artist, is actually a puzzle. And with the help of some bizarre new acquaintances - including a museum...