A Ghost in Monte Carlo

Pawn of Vengeance
It was the gayest season Monte Carlo had ever known, and of all the beautiful bejewelled women, Mademoiselle Fantôme was causing a sensation. Who was the exquisite “ghost,” with her shining golden hair and dreaming dark eyes? Why did her formidable aunt guard her so carefully?
Even Mademoiselle herself did not understand the seductive role she was playing. But her troubled young heart knew that evil was drawing close to her, that she was a pawn in a mysterious plot to avenge an old wrong.
Too late, she discovered that jealousy and bitterness were threatening to destroy her new-found love.

i read this book in high school...and still remember the story duno how..well it goes as such mistral is a girl who lives with her aunt and who always dresses in grey, which makes people curious ...but later she realises that it was a scheme set up by her aunt and must not follow her orders in order to save her love...

From the Back Cover:

"In the gayest season Monte Carlo had ever seen, two women caused a sensation. One was elderly, her expression malignant, secretive and evil; the other was exquisitely lovely and passionately alive. But she was also a myster woman, about whom nothing at all was known save that she always dressed in grey and called herself Mademoiselle Fantome..."