This is the second tale in the series of 5 books, aimed at children aged 7-9 years who are able to read independently. This is the story of the drowning of Cantre'r Gwaelod in Cardigan Bay. The birthday party for Princess Mererid is being held in the palace, but the watchers Gwyn and Llewelyn must keep watch on the dike. Will they manage to warn everyone about the storm in time?