Ivy Tree by Mary Stewart
Mary Grey is enjoying her day off by taking in the local tourist sights near her new home. She has recently left her native Canada to return to Northumberland where her great-grand parents had been born. Suddenly a young man confronts her, calling her Annabel and insisting that she is his cousin who disappeared eight years earlier. Mary manages to convince him of her identity but soon finds herself embroiled in a plot to impersonate the missing Annabel in her family home, Whitescar.
Gradually it becomes apparent that all is not quite as it seems, everyone there seems to have a secret, her Grandfather has not disclosed who will inherit the family farm, 'cousin' Con has not revealed the depths of his ambition, the missing Annabel left behind secrets when she fled, even the estate itself has been keeping things hidden. Eventually all is revealed with the usual Stewart flair for drama and romance.
I have always enjoyed a good Mary Stewart novel and this one did not disappoint. She is most well-known for her Merlin & other middle ages fantasy. But she wrote a lot of suspenseful romantic fiction in the 1950's & 1970's. She really does make you read and re-read passages as so much description and in this case clues to the ending are all there right for you. Stewart is able to write such intense characters but not so it feels cliched.