Raised in Prison, I Married a Dying CEO

Nancy has a debt to collect from her father. Fifteen years ago he left her at the gate of a prison and did not come back, and she grew up inside it. An old man who worked there as a guard took her as his apprentice and passed on everything he knew. By the time she was grown she ran the prison from the inside and had the worst men in it answering to her. She gets out, and her father has a use for her right away. Her stepsister is supposed to marry Leonard, the young CEO of the Lu Group, and Nancy is sent to the wedding in the stepsister's place. Leonard has been poisoned with something no one can name. He cannot speak, and he is close to death. The Lu family is spending everything it has to find a healer called the Medical Immortal. That is the name Nancy went by, and nobody in the house has put the two together. She keeps quiet about it and begins settling accounts with the people who wronged her.