On the idyllic island of Nantucket, the five Fairchild children enter a sandcastle competition while staying with their grandmother for the summer holidays.

They spend all day constructing a beautiful fort complete with soldiers, a moat and turrets made from shells and debris washed up onto the white sandy beach. They feel sure they will win!

But that night one of the children has a vivid dream about the sandcastle and the following day they are all amazed to discover that the dream has indeed come true.

Are they still in with a chance of a prize?