The Shadow of Your Smile - Mary Higgins Clark

At age eighty-three and in failing health, Olivia Morrow knows she has little time left. The last of her line, she faces a momentous choice: expose a long-held family secret, or take it with her to her grave. Now thirty-one year old paediatrician Dr. Monica Farrell, stands as the rightful heir to what remains of the family fortune. But in telling Monica who she really is and getting what is lawfully hers, Olivia would have to betray her family' wishes and reveal the story behind Monica's ancestry.