A sea battle in 1683 between a Spanish galleon and a smaller French corsair results in the galleon being sunk, its treasure stolen and the Spanish captain and two ladies taken prisoner for ransom. Later a storm howls for three days and pushes the corsair into a large cave where a landslide removes all trace of it from the world outside. Three hundred and thirty-five years later the Franks twins, on holiday from their home in Norfolk to their...