Good one, quite a simple one really. 19 year old girl brought up by her grand dad in an isolated Cornish castle. When grand dad dies, the girl is directionless. But granddad makes a provision in the will for a male cousin to inherit the castle and pick up the girl in the bargain, as a wife. Sounds somewhat callous, but very well intentioned.
The girl is preparing herself for Part 2 of her previous life but this time with cousin Mark, assuming he is a middle aged uncle type good samaritan. But our cousin is actually a drop dead gorgeous hunk, and half Latin to boot! Obviously perfect hero material :)
Now the only twist in the story is that he doesn't present himself to the girl until quite late. However, he does steal her heart much before while appearing in disguise. So when the disguise ends, she is miffed and also disillusioned by his actual identity. Her disappointment is quite justified.
The guy on the other hand seems quite smitten right from their chance anonymous first meeting. He has been keeping a protective eye on her all along. Finally, when all confusions are cleared, he does make a charming lover and super husband. Jackpot catch !!