A Castle Of Dreams (Barbara Cartland's Pink Collection 59‪)‬

Can money buy you happiness? Impoverished Lady Viola and her twin brother David Northcombe find that their fortunes change dramatically when their entrepreneurial father dies unexpectedly, leaving them a vast fortune that will change their lives forever.
Returning home to England, still reeling from their dramatic change in circumstances, fate seems to have smiled on them when the handsome, but impoverished, Duke of Glentorran dramatically rescues them from the perils of the sea off the coast of Scotland.