My Hidden Heiress: CEO Daddy's Secret Baby

The Thorne family carries a genetic trait, rare and passed down the line, that shows in every child born to it. A doctor who knows the family can recognize it on sight. Six years earlier, Clara was set up. A scheme put her in Ethan Thorne's bed for one night, she became pregnant, and word of the pregnancy went around the whole school. She was expelled and raised the child, Mandy, on her own. In the present Clara takes Mandy to the hospital with a fever. The doctor who examines the girl grew up with Ethan and recognizes the Thorne trait in her. He tells Ethan straight away. When the Thornes hear that Ethan has a daughter they are delighted, and Ethan's grandfather orders him to bring his great-granddaughter home without delay. Ethan starts looking for the child and her mother. A woman who was at school with Clara, and who is jealous of her, keeps steering him wrong, so that each time he comes close to the answer he misses it.